The difference in treatment of unused sick leave has been a sore point for FERS employees since that system was created in the 1980s. The benefit is often a valuable one for CSRS employees, since many employees carry a year or more of unused sick leave into retirement and under the CSRS formula each additional year of service beyond 10 years boosts an annuity by 2 percent. The disparity also has led to widespread allegations that FERS employees burn off sick leave when it is not justified, especially as they approach retirement. Several studies have lent support to that theory, with one report last year finding for example that FERS employees who are eligible to retire or within two years of eligibility use 25 percent more sick leave than their CSRS counterparts, and that those who are eligible to retire use 35 percent more. Data from DoD from several years ago showed that the average CSRS employee carried more than 1,000 hours of unused sick leave into retirement, while the average FERS employee carried less than a third as much.