Generally how much shoulda good investment fund return per year?

The rate of return is dependent on how much risk you are willing to stand.

This is usually age-dependent and income (and prospective income) dependent.

The answer is different for the same aged truck driver making $50k/year and a surgeon making $350k/year as well.

Without all those details, a good rate of return is impossible to universally name.

As someone else said, the risk (which means volatility either up or down) is generally related to expected return. Also, consider looking at the rate minus inflation (the "real" rate) as a guide.

Historically stocks have returned more or less 8% on average per year over the long haul. That means some years were up much more, and some down significantly, and some where nothing much happened. But over 50 years or so it worked out to the same as 8% each year. Take out inflation and you're probably around a little over 5%.

The problem is that you can never look at a fund's returns in any given year and conclude very much. Often the largest factor is the expense ratio. If it's high, their long-term prospects usually aren't as good.

S&P 500 is 10% if you include dividends