Historically, as a guideline, you'd have made about 7% p.a. on average, well above inflation. The question is whether you can handle the drawdown (can you keep your nerves during a crash?)
then again: beware of averages. Historical PE ratios are quite high (though EV/FCC would be more instructive) - so it is unlikely that the next couple of years will bring 7%. We're living in a world of free money: if central banks change interest rates the party could come to an end.
