If you wanted reliable returns over the length of one year, you shouldn't have bought stocks at all. Index investing wins in the long term, but 10-20 years even may not be enough.
If you want to beat the average for the market, you have to be able to identify a stock which is incorrectly priced. But stocks are traded by rather a lot of people, at the present market price, which you think is an incorrect price. That means you must know something that all of those people either don't know, or didn't correctly act on.