These are the average returns of all the mutual funds vs their respective stock market indices over a long time frame

Taken from Lubos Pastor and Robert F. Stambaugh, “Mutual Fund Performance and Seemingly Unrelated Assets,” Journal of Financial Exonomics, 63 (2002).
If you get a chance, read this research paper. They analysed mutual funds from various countries in different periods to arrive at these results.
I am advertising this paper here because it goes well with my original stance 1 and 2