Do you get a sick feeling in your stomach every time you have to prepare for benefits selection or plan design/renewal? Over the past 10 years, healthcare costs have risen on average 4.15% per year, according to Mercer. This average increase would be more had employers not made a number of plan changes, the most common of which have been raising deductibles and offering less generous plans. Smaller employers have seen a much higher percentage increase than large employers.