Anniversaries are times for reflection, and last week's 6th anniversary of the signing of the Patient Protection and Affordable Care Act into law is no exception. It would be hard to ignore or dismiss the health care reform law's accomplishments.

The biggest ACA success has been the reduction in the number of Americans without health insurance. The most recent Census Bureau report, for example, showed a steep decline in the number and percentage of uninsured Americans.

In 2014, 33 million people lacked coverage, down 8.8 million from 41.8 million in 2013. Similarly, the percentage of the population who were uninsured dropped to 10.4% in 2014 from 13.3% in 2013.

The reasons for those declines, which we believe will be even steeper by the time of the next Census Bureau report in September, are directly attributable to the ACA.

Close to 13 million people, many of them previously uninsured, signed up for coverage in public exchanges during the 2016 open enrollment. More than 80% of those individuals, because of their low incomes, are eligible to use federal subsidies — also created by the ACA — to offset all or part of premiums they pay for exchange coverage.

Other ACA provisions, including those giving states big financial incentives to ease eligibility requirements for Medicaid programs, also have helped make a dent in the number of uninsured.

The benefits of expanded coverage are obvious and important. For individuals, it means they are more likely to have medical problems treated promptly rather than waiting until those problems mushroom into conditions that are far more expensive to treat.

Expanded coverage rates also benefit employers in the form of cost containment. To the extent more people have coverage, health care providers will have less need to shift uncompensated care costs, in the form of higher charges, to insured patients.

That said, the law is not without problems.

One obvious example is its 40% excise tax on group health care plan premiums that exceed certain amounts. The assumption that the tax will raise tens of billions of dollars in federal revenue as employers raise employees' taxable wages to offset benefit cuts to avoid the levy is nonsense. That provision should be killed ASAP.

Above all, we hope lawmakers and the next president focus on improving the law, not repealing it.