TheKaiser Family Foundation finds that from 2008 to 2018, averagepremiums for a family on a large employer health plan increased 55percent, while average cost-sharing increased 70 percent. (Image:Shutterstock)

Traditionally, generous health coverage has been one of thebenefits of working for a large employer. Big businesses and largepublic sector agencies are able to leverage their size to negotiate better rates with insurers.

However, those with access to large employer health plans havenot been insulated from the rapid increase in health care costsover the past two decades. As insurers have demanded higher prices,employers have shifted a bigger share of the cost onto employees inthe form of higher premiums, copays and deductibles.

Related: 10 states paying the most for employer-sponsoredhealth care premiums

A new study by researchers at the Kaiser FamilyFoundation finds that from 2008 to 2018, average premiumsfor a family on a large employer health plan increased 55 percent,while average cost-sharing increased 70 percent. During that time,average wages only rose 26 percent.

As a result, average annual health care spending by familiescovered by large employers has increased by two-thirds, from $4,617to $7,726. For lower-wage employees of large firms, that amounts toa significant share of their annual income.

Most of the change is due to the cost of health care, ratherthan employers shifting the burden to workers. Between 2008-18, theaverage portion of health care costs covered by employers onlydeclined slightly, from 68 percent to 66 percent.

In fact, the average large employer covers a larger share ofprescription drug costs now (89 percent) than they did a decade ago(80 percent). The average employer share of inpatient services hasremained flat, at about 93 percent. Meanwhile, employers havedecreased the share of outpatient services they cover from 84.8percent to 80.8 percent.

Perhaps the most notable change in plan design has come from therise in high deductibles. Far more workers have annual deductiblesand the size of the average deductible has risen significantly. In2003, only 20 percent of the average employee's out-of-pocket costswent towards a deductible. By 2017, deductibles accounted for 51percent of out-of-pocket spending.

Read more: 

• Employer-sponsored health insurance still the mostpopular option
• Employer-based health care hits poorer Americans'paychecks hardest
• 4 reasons employer-sponsored health insurance won'tgo away