While the political world has spent the past several months watching enrollment numbers in Obamacare health insurance marketplaces, maybe we should have been focusing on employer-sponsored insurance.

A new survey from Rand Corp. estimates 9.3 million people were newly insured between September 2013 and March 2014, a trend that was mostly driven by an enrollment increase in employer-sponsored plans.

The growing market for employer-sponsored insurance is still the nation's most common source of coverage. The survey, which comes with some caveats, finds that of the previously uninsured who gained new coverage, 7.2 million were covered by employer plans, 3.6 million were covered by Medicaid and 1.4 million signed up through the Obamacare exchanges. In all, employer coverage increased by 8.2 million since September, Rand said.

Fewer than 1 million people who previously had individual coverage are still uninsured, Rand found. What’s not clear is how many had their plans cancelled or decided their coverage was unaffordable. In all, people who lost previous coverage in the individual market made up less than 1 percent of nonelderly adults, Rand said.

The survey is, of course, just that – survey. It doesn’t tell us everything about the new coverage landscape, and it doesn’t fully include the late March enrollment surge. Rand researchers said the margin of error is pretty large – the topline 9.3 million figure comes with a 3.5 million margin of error.

That said, we do have a good sense that the uninsured rate is dropping. Gallup reported Monday that the uninsured rate is at its lowest point since 2008:

What’s driving enrollment in employer plans the past six months? The survey doesn’t attempt to answer this question, but it’s another thing to think about when considering the impact of the health-care law.