I invite readers to submit proposed answers to the above question.  As recently as some months ago I might have thought the best answer was the classified "TOP SECRET" information of the State and Defense Departments; but we have more recently learned that much of that information turns up on "please hack me" private servers of the top officials.  Another good candidate until recently might have been the personal information submitted by taxpayers on their returns; but again, it seems that those secrets have been rather poorly kept.

So a better candidate for "best kept secret" would be in the category where the government just avoids collecting the relevant information because they suspect that the answer if known would be too embarrassing to the official party line.  Therefore consider as a candidate for "best kept secret" the statistics for the number and percent of people in the U.S. without health insurance, the so-called "uninsured."

Do you remember when the greatest crisis facing the United States was the "crisis of the uninsured"?  That would be back during the GW Bush administration, when you couldn't go through a week's worth of the output of any "mainstream" media publication without finding at least one heartrending story about the sufferings of those without medical insurance.  Today, such stories have almost completely disappeared.  Can you remember the last time you saw one?

Undoubtedly, you may be thinking, that must be because Obamacare fixed the crisis.  Not only did we get lots of new subsidies and a huge Medicaid expansion, but we got the "employer mandate" and the "individual mandate."  Today, it has become literally illegal not to have medical insurance.  Therefore, everybody has it.  Right?  Or alternatively, could it be that the numbers of uninsured have not changed much at all and you don't read about it because the government doesn't collect the information and the press just isn't interested while their guy is in the White House?

If you go to look for the information as to the currently-uninsured, you will find that definitive numbers are impossible to find.  Wait a minute -- Can't the government just go to each insurance company as of a certain day and get the number that each is insuring on that day, then add their own numbers for Medicare and Medicaid beneficiaries on that day, subtract from the total population, and give us the answer?  I sure don't know any reason why the government can't do that.  But as far as I can find, they don't.

Instead what happens is that some private companies (e.g., Gallup) do surveys where they ask people whether they have insurance or not.  Within the government, as far as I can find, the CDC has done a similar survey (why is this part of their mission?), and that's it.  There's no information at all coming from the obviously definitive source of the insurance companies.  As to the population surveys, whether by the private companies or the CDC, the data are reported in inconsistent and confusing ways that make it as difficult as possible to tell how much effect Obamacare has had on the size of the uninsured population.  And the CDC study is obviously wildly spinning like a top to make Obamacare seem as much as possible at least a little success.

But even without definitive numbers, there is enough data available that you immediately realize that once you get past the new handouts of "free" coverage in the law (i.e., the Medicaid expansion and the requirement that children up to 26 be covered by their parents' policies) the effect of Obamacare has been exceedingly minimal.  Here is a private but very pro-Obamacare site called Obamacare Facts that at least puts some of the numbers in semi-usable form.  Some highlights:

• According to the US Census Bureau, before the ACA in 2009 about 48.6 million or 15.7% of the population was uninsured. A 2015 study by the CDC using Census data showed the total uninsured rate as 9.2% and the uninsured rate for the 18 – 64 demographic as 13%.         

OK, 15.7% of the population to 9.2% sounds like a substantial decline in the uninsured population -- it would be around 20 million people.  But how much of that consists of simply handing out new completely free coverage to the non-poor in the form of Medicaid and CHIP expansion?  Again from Obamacare Facts:

• 10.8 million more enrolled in Medicaid or CHIP since Oct 2013 (estimated at 11.7 million as of May 2015). Not all who enrolled were ineligible before the ACA, but instead enrolled due to the woodworking effect (increased awareness under the ACA leading to more sign ups).  

That 10.8 million would be more than half of the increase in the "insured."  As to the so-called "woodworking" effect, it's up to us to guess whether that is substantial or not.  It's not clear to me that it makes a whole lot of difference to anybody whether they are insured or not if you have the right to sign up any time you feel like it for free care (including up to two months retroactive!).

And then there's the other free category, the under 26-year-olds who got to stay on their parents' coverage.  How many of those?

• It’s estimated by HHS that 5.7 million young adults (aged 19-25) stayed on a parent’s plan until age 26. That is 2.3 million who stayed on their parents plan from 2010 to 2013 with an estimated 3.4 million gaining coverage from 2013 to 2015.     

Put the last two categories together, and you have 16.5 million -- leaving only about 4 million people as having gained coverage from the entire rest of the law.  OK, it's a few more if you believe in the "woodworking" theory.  Do you mean that all that stuff about individual mandate, employer mandate, everybody must have coverage, tax penalties,  government exchanges, gold, silver and bronze plans, subsidies up to 400% of poverty level, "risk corridor" giveaways to insurance companies to get them to participate, newly-created co-ops, two thousand pages of statute, etc., etc., only led to less than two percent of the population agreeing to add health insurance where it would cost them even one dime of their own money?

So how many people total have actually signed up via these state and federal exchanges?  For that, turn to the New York Times, which carried an article titled "Little Growth Predicted On Health Exchanges" in the October 15 issue.  I'll bet you missed it -- it was on page A20.

About 9.9 million people had coverage through the federal and state insurance exchanges at the end of June, and administration officials predict that the enrollment will decline to 9.1 million by the end of this year.      

That 9.1 million would be about 3% of the population, but of course some of them replaced lost employer coverage, so give the government credit for around a 2% increment in the "covered" population -- although most of those with some level of government subsidy.  But isn't this just the beginning?  Won't Obamacare continue to expand until everybody is covered?  Here's why they saved this story for page A20:

After an elaborate analysis of demographic data, Sylvia Mathews Burwell, the secretary of health and human services, said that 10 million people were expected to have marketplace coverage at the end of next year, up only about 100,000 from recent levels and millions short of earlier projections. . . .   The Congressional Budget Office predicted in March that enrollment through the exchanges would reach 11 million this year and 21 million in 2016.

Oops!  A projected more-than-doubling by the end of 2016 of those insured through the exchanges, from 9 million to 21 million has just been turned into a projected increase of 100,000.  So, Ms. Burwell, how are you going to spin this one?

Because of gains in coverage in the last two years, Ms. Burwell said, there are fewer uninsured Americans, and “they are a little harder to reach.”   

Good understatement, Sylvia!  I'd say we're talking about around 30 million or so people left, and it looks like the prospects for moving that number down any further via the Obamacare Rube Goldberg mechanism are about zero.  If 48 million uninsured was a desperate crisis, what now?

In the New York Post on Monday, Betsey McCaughey posits that those people who just won't sign up are largely the healthy young, and that the Obamacare "death spiral" has begun.  Of course, it will take a long time for this to play out, maybe 20 years, at enormous cost to the taxpayers.  (The Weekly Standard projects the ten-year cost of Obamacare at $2 trillion.)  But I can't see how McCaughey is wrong.

No wonder the government isn't going out of its way to collect data on this subject.  Hey, down in Venezuela they have stopped collecting data on GDP and inflation.  That's how they prove that socialism works.