Oct. 9 (Bloomberg) -- U.S. state pension plans are strengthening for the first time in six years as rising contributions and rallying stocks ease a fiscal strain that’s vexed municipal leaders since the recession.

The median state system last year had 69.3 percent of the assets needed to meet promised benefits, up from 68.7 percent in 2012, according to data compiled by Bloomberg. It was the first increase since the start of the 18-month recession that ravaged retirement assets and led some officials to skip payments as tax revenue sank. Illinois and New Jersey, with the weakest state credit ratings, saw funding levels set new lows for the period.

Buoyed as the Standard & Poor’s 500 index set record highs, the nation’s 100 largest public pensions earned about $448 billion in 2013, the most in at least five years, Census data show. At the same time, governments added a record $95 billion to their plans as they socked away rebounding tax revenue toward obligations to retirees.