Mutual fund fees fell slightly last year, driven in part by investor demand for low-cost funds.

Those findings are in separate reports issued Monday by Morningstar and by the fund industry's trade organization, the Investment Company Institute.

The annual reports examined average fund expense ratios. That's the fee investors pay each year, expressed as a percentage of a fund's assets.

Morningstar found the typical investor paid 0.75 percent last year, or $7.50 for every $1,000 invested. That's down from 0.77 percent in 2010. Morningstar's figure is the average for stock funds and bond funds, as well as funds investing in alternative assets.

The ICI found investors paid 0.79 percent at stock funds last year, while bond fund investors paid 0.62 percent. Both are down slightly from 2010.