U.S. stocks crept to a record as the S&P 500 nudged higher after a quiet Tuesday of trading. The main measure of Wall Street's health rose 0.2% to finish just above its all-time closing high set last month.

However, the S&P 500 ( ^GSPC -0.01%) is generally considered the best barometer for the overall U.S. stock market due to its scope and diversity. Read on to see the S&P 500's average return over the last decade, and to learn what Wall Street expects in the future.

U.S. stocks rallied to the brink of a record after more companies reported fatter profits than expected. The S&P 500 rose 1% Thursday.