Fewer venture capital firms this year have been successful at raising money for funds that will aid promising companies. The number of funds that raised money in the first half of the year was the lowest level since 1995, according to national data released Monday from Thomson Reuters and the National Venture Capital Association.

Venture capitalists raised $10.2 billion for 76 funds in the first six months of the year, according to the data. In dollars, that was a 67 percent increase compared to the same period last year. However, the number of funds declined by 15 percent.

"While a smaller venture industry will intuitively produce higher returns, it is critical that the mix of funds remain geographically diverse and cover a broad base of industries if we expect to contribute to economic growth and innovation at the levels we have historically," said Mark Heesen, president of the National Venture Capital Association.