“Over the past few years, the overall economic situation kept consumer spending on discretionary items—including health care—down, and we observed a lower rate of premium increases,” said Tim Nimmer, chief health care actuary at Aon Hewitt. “Now, with employment rates stabilizing, individuals are feeling more secure about their financial situation and have been willing to re-engage in using the health care system. As these utilization rates increase, we expect to see health care cost increases follow.”

In addition to the employee premium, workers on average will pay another $2,487 in out-of-pocket costs, which is up more than 8 percent from $2,295 in 2014. By next year, worker out-of-pocket costs will have almost doubled from $1,276 in 2009.

The bigger picture from the firm's analysis? All told, these projections mean that over the last five years, employees' share of health care costs—including employee contributions and out-of-pocket costs—will have increased more than 52 percent, from $3,389 in 2010 to $5,151 in 2015.

Aon Hewitt's figures are based on more than 560 employers representing more than 13 million insured employees.

To combat the costs, the consulting firm said employers are doing a number of things. These include offering high-deductible health plans (15 percent of companies offer a HDHP as the only health plan option today, and another 42 percent are considering doing so in the next three-to-five years); gating health benefits (more than 60 percent of companies plan to gate employees to richer designs in the next three-to-five years) and adopting pay-for-performance strategies.

Employers also are increasingly managing dependent eligibility and subsidies, their research shows. Almost a quarter of employers (22 percent) have reduced subsidies for covered dependents, while 18 percent added a surcharge for adult dependents with access to other health coverage. An additional half of companies are exploring such approaches over the next few years.