Employee contributions to Health Savings Accounts grew last year, according to research by J.P. Morgan Treasury Services.

The study revealed that the percentage of HSAs with balances consisting of more than $2,000 increased to 31 percent in 2009, up from 20 percent in 2008. Nearly 70 percent of employees contributing to an HSA put more money in than they needed for health care expenses.

Even though most transactions with an HSA account took place at drugstores, the most expensive uses went toward payments for medical and dental fees, according to the study.

HSAs are accounts that are funded by employees with pre-tax dollars through their employer to help cover medical costs. Typically HSA plans are "use it or lose it," meaning that contributors do not get back unused money.

Contributing to an HSA can result in large savings. The study found that in 2009, the average employee contributed $1,653.24 to an HSA, saving $462.92.

The data was gathered from over 500,000 HSAs held through J.P. Morgan.

According to the government, the maximum contribution employees can make will be $2,500 to an HSA starting in 2013.