The number of Minnesotans with employer-based health insurance dropped between 2009 and 2013, sparking concern from state health officials, but also hope that the state’s MNsure insurance exchange has arrived in time to pick up the slack.

The state’s overall uninsured rate declined from 9 percent in 2009 to 8.2 last year, according to survey results released Friday by the University of Minnesota and the state Health Department.

But that reflected increases in public coverage for the poor and elderly. The share of Minnesotans with benefits through their jobs declined from 57.4 percent to 55.2 percent over the same period, despite improvements in employment and the state economy.

“Because employer-based coverage is the bedrock of Minnesota’s comparatively low rate of uninsurance, it is especially concerning that those who do have access to coverage through their jobs are choosing not to take it,” said Dr. Kathleen Call, a University of Minnesota public health professor and co-leader of the survey.

The survey was conducted from August through November last year, so it doesn’t account for changes in insurance coverage caused by MNsure, the exchange created under the federal Affordable Care Act. Benefits purchased on the exchange didn’t take effect until 2014.

The survey does reflect earlier coverage expansions under the federal law, which allowed more low-income adults in Minnesota to qualify for public benefits and young adults to linger on their parents’ plans until age 26.

The decline in workers with benefits through their employers continues a decadelong trend; more than 68 percent of Minnesota workers had employer-based coverage back in 2001. But it isn’t just because employers are dropping benefits altogether.

The share of survey respondents connected to employers that offered coverage did drop from 78.2 percent in 2009 to 76.3 last year. But there was a more rapid decline in the share of people who had access to employer-based benefits and opted to use them.

Premium costs have generally outpaced wage growth over the past decade, so workers have been recalculating whether the costs of health insurance are worth it, said Stefan Gildemeister, director of the Health Department’s health economics program.

In some cases, the costs of plans have increased while employers have reduced the share they pay or the benefits levels provided.

“Year after year, I think we’re paying more for employer coverage,” Gildemeister said. “So individuals are asking themselves: ‘Is that the right trade-off I can make at this point?’ ”

At the same time, state health officials say health plans offered on MNsure may offer an alternative for people who find their workplace plans unaffordable. As a result, they expect the share of Minnesotans enrolled on the individual market to increase when they conduct their next survey, in two years. As of 2013, only 5.4 percent of Minnesotans bought health insurance on the individual market.

One challenge that turned up in the survey, however, is a lack of awareness about MNsure and the Affordable Care Act. Less than half of those surveyed felt they understood how federal health reforms and MNsure could benefit them. Among the uninsured, only one-third felt informed.

“Those most likely to be impacted by the changes are the least likely to know about them,” Gildemeister said.

The good news, state officials said, is that awareness of MNsure and its offerings improved among survey respondents after open enrollment started in October.