Warren Buffet says 6-7%, and by rules of compound interest, that 3-4% difference is a lot over 75 years, so I'd say "high." I'd guess a really good, modern, algorithm from the past couple years could average, maybe, 15%? I actually have no idea.
There’s no need to quote authority; this is public data. The annualized return on the S&P 500 over the last 75 years (Mar 1943 - Mar 2018) was 11.35%. Adjusted for inflation, 7.45%.
My personal overall rate of return is 13% over the last 20 years, without any algorithmic bullshit. Just 80% in a basket of dollar cost averaged mutual funds and 20% in cash strategically invested when opportunity arises.
Iirc, last year was around 14% in the mutual funds, with the “fun money” mostly cash.
