A CBO report released the same day as the Mueller report found the number of uninsured Americans has increased from 27.5 million to 28.9 million over the last two years. According to the CBO, the jump is largely the result of the sharp increase in premiums over the same time period. From the Hill:

One of the main areas of decline the CBO found was among Americans who purchase coverage on the individual market outside of the federal and state-run ObamaCare exchanges.
In 2016, 7.4 million people purchased coverage outside the exchanges. In 2018, that number dropped to 4.9 million.

Additionally, the number of people who bought unsubsidized insurance through the exchanges has declined slightly, from 1.6 million people in 2016 to an estimated 1.3 million in 2018.

In both cases, experts attributed the decline to rising premiums.

Over at Vox, Sarah Kliff notes that all of this increase happened before the repeal of the individual mandate kicked in earlier this year:

It’s notable that these declines in coverage are happening even though Republicans were unable to repeal the Affordable Care Act — and all before the repeal of the requirement to carry health insurance took effect (that provision only kicked in at the start of 2019). The rising uninsured rate is happening at a moment when, on paper, Obamacare looks a lot like it did under President Obama.

There is some evidence that all the discussion of Obamacare repeal may be depressing insurance enrollment. A YouGov poll at the end of 2017 found that 31 percent of Americans believed Republicans had successfully repealed the Affordable Care Act. More recent polling from the Kaiser Family Foundation finds that 17 percent of Americans believe the law has been repealed and 14 percent aren’t sure if it’s still standing. With that many Americans believing Obamacare doesn’t exist, it makes sense that you’re seeing lower sign-up rates in both the individual markets and Medicaid.

Maybe there’s something to this but we don’t know that the people who think Obamacare has already been repealed overlap with people in the market for Obamacare. Maybe the people who aren’t sure what is happening with the law are people who already have insurance through work or a spouse. In other words, those people who are looking for insurance would probably be more motivated to find out what the status of the law actually is at this point. So attributing this increase in the uninsured rate to ignorance rather than price increases seems speculative.

At a new site called Issues and Insights, John Merline argues the decline is entirely the result of price hikes:

All of the increase in the uninsured over the past two years — all of it — is the result of the massive rate increases Obamacare’s mandates and regulations caused. According to the Health and Human Services Dept., premiums in the individual insurance market doubled from 2013 to 2017. They shot up again in 2018.

For those eligible for Obamacare subsidies, the rate increases were meaningless. The amount they had to pay didn’t change much, and in many cases went down.

But for the millions of middle-class Americans who buy insurance coverage on the individual market and aren’t eligible for Obamacare subsidies, the result has been financially devastating.

Whatever the case, there’s reason to think that the repeal of the individual mandate will result in even more people responding to the high prices and high deductibles by opting out. Obamacare has never really worked as expected but it was never expected to work at all without a mandate.