What you've probably noticed anecdotally with your clients is an identifiable trend: Many more people are staying in the workforce longer-and it's likely because they need affordable health insurance, according to a new report.

According to the Employee Benefit Research Institute, the percentage of those ages 55 or older in the labor force increased from 29.4% in 1993 to 39.4% in 2008. For those ages 65-69, the percentage increased from 18.4% in 1985 to 30.7% in 2006. "These trends mark a significant change in behavior for individuals in these age groups, and are likely driven by their need to obtain affordable employment-based health insurance and to accumulate retirement savings," EBRI reports in Employment Status of Workers Ages 55 or Older, 1987-2008.

"Workers who have access to retirement plans and retiree health insurance through their employment face increasing responsibility for contributing to these benefits. Consequently, they need to save more of their income for these purposes. The main option for doing that is to delay retirement and remain in the labor force, so as to postpone the need to pay these expenses and continue to accumulate savings," the report adds.

The report looked at various age groups and found that workers ages 65-69 had the largest percentage point increase in working full time, full year, from 36.4% in 1987 to 51.6% in 2007 (decreasing to 49.8% in 2008). Workers in the age 70?74 group also showed a significant increase in full-time, full-year work, including a small increase in 2008 (27.6% in 1987 to 39.6% in 2008).

However, the recession in 2008 took a toll on the number of older workers working full-time jobs. "The percentage of workers age 55 or older who work full time, full year steadily increased from 54.2% in 1993 to 66% in 2007, before a decline in 2008 to 63.9%," EBRI says. "The percentage of workers in this age group who were part-time, full-year workers has remained virtually constant from 1987-2008 at approximately 13-14%. Those who worked only part year, either full time or part time, declined from 32% in 1990 to 20.9% in 2007; this increased to 22.7% in 2008."

Interestingly, the percentage of workers who are offered health insurance by their employers has been rising. Employees who were not offered health insurance was roughly 40% through 2003, and has been falling since then, to 24% in 2009, the report says. Most workers who don't have insurance said it was because of the cost-either because the cost was too high to participate in their employer's plan or to buy health insurance on their own.