Contributions to 401(k) plans increased in the last year, according to the Principal Financial Well-Being Index.

Conducted online by Harris Interactive, the index surveys retirees and American workers at businesses with 10 to 1,000 workers.

The percentage of workers who are eligible for defined contribution retirement plans and chose to participate increased to eighty-five percent, up from 81% a year ago.  Eighteen percent said that they have increased their contributions, up from 13% a year ago.

“It may be a sign the economy is improving that some workers are comfortable increasing their 401(k) contributions instead of dipping into retirement savings to cover daily expenses.” Luke Vandermillen, vice president of retirement and investor services at The Principal, said in a press release.

About a third of employees surveyed said they planned to pay off credit card debt in 2011. Among the retirees, 19% planned to cut their spending by a specific amount each month and 17% said they would pay off credit card debt.