Despite the current market volatility, workers at private U.S. employers may be contributing more to workplace retirement savings plans.

Fidelity Investments, Boston, says the average contribution at the 16,723 corporate defined contribution plans it maintains increased to $3,187 in the first half, from $3,142 in the first half of 2007:

The plans included in the analysis have more than 11 million participants.

The average contribution for workers who contributed to the same plan in both periods increased to $3,512, from $3,283.

Because of a slump in investment values, the average account balance fell 7.5%, to $64,000, at the end of June.

The average account balance for employees who have participated in the same plan since Jan. 1, 2007, fell 1%, to $71,500.

The S&P 500 index fell about 15% over the course of that same period, Fidelity notes.

Other Fidelity plan contribution findings:

- Only 9% of the workers included were contributing as much as federal law permits them to contribute.

- About 38% of highly compensated employees max out their retirement plans.

- Only 3.8% of non-highly compensated employees max out their plans.

- The percentage of workers with a plan loan outstanding fell to 19.2% at June 30, down from 19.4% a year earlier.

- The percentage of workers taking a “hardship withdrawal” due to an immediate or severe financial need increased to 0.6%, from 0.56%.