your high return in the year 2013 had to do with the type of inestments your portfolio was invested in. Look at what it is invested in. Also, if the 401k administration is including your contributions it could be misleading.
You're obviously invested mostly in stock funds. Stocks had a huge runup last year - that's why your return was so high. At 22, you should be fairly aggressive in your asset mix - but never overlook the fundamental value of diversification.
How much you contribute has nothing to do with your rate of return.
Last year was a pretty good year for the stock market.
ETA: I forgot to mention that the broader US stock market averages about 10% per year over the past century or so. Aggressive growth and certain "hot" areas like health care & technology will do better than that. Again, remember that wide swings are normal. You can't look at monthly, quarterly or annual returns (except to compare performance to OTHER investments during the same time period). Most stock market swings (up and down) happen in powerful brief spurts. Just don't pay attention if it bothers you. :-)
If you are invested in aggressive growth stocks (as you SHOULD be at your age), you can expect to watch your account balance double in some years and be cut in half other years. Wide swings are normal. Just remember, when the market goes south it's only temporary...and it's a GREAT opportunity to buy more shares "on sale" since prices are lower.
You are doing great! My only suggestion (not that you asked, sorry) is to make sure you have selected the ROTH 401k option if your employer offers it. When you retire you'll be stinkin' rich and not paying any taxes. :-)
Your rate of return is high for several reasons, 2013 was a fantastic year in the stock market so depending upon your allocations you may have just hit the sweet spot. Consider your real rate of return starts at 70% if you consider the company's match as "return" and technically it is. The "normal" rate of return in the market is between 6-9% in equities over the very long run. You are on the right track with your 10% contribution, your company match.. .and a solid allocation and you will have a great portfolio value in 30-40 years... in the millions if you continue.
I started investing 2% in my 401k at 19 years old in 2010 and currently 22 years old. In 2013 I increased my contributions to 10% since my employer matches 70% of the first 10% contributed. Last year I had a 33.5% rate of return. Why is my rate of return so high? Is it because I haven't invested long enough yet? I know I increased my contributions but I don't think it will be around 33.5% of a return every year. For 2014 I currently have a 5.53 rate of return. What is an average rate of return for aggressive investing 401k?