The number of investors with at least some confidence in U.S. capital markets has increased slightly since the end of last year, according to the Center for Audit Quality.

Almost two thirds (65 percent) of investors with at least $10,000 in investments have at least some confidence in the market, an increase of 4 percent since 2011, says the Sixth Annual Main Street Investor Survey taken of 1,003 investors.

The survey by the Center for Audit Quality, a public policy organization based in Washington, D.C., also found 70 percent of investors think the economy will stay the same or improve. Only 20 percent think it will get worse.

Similarly, 64 percent feel their personal financial situation will stay the same, while 25 percent feel it will improve over the next year.

The four top economic concerns investors have are not having enough money for retirement, not being able to afford health care, not being able to maintain their standard of living and losing their jobs.

On the other hand, confidence in capital markets outside the United States fell by 8 percent to 35 percent.