After 10 fat years for stock investors a lean decade is looming

Here is the article.

Let me review the paragraph and list a few facts in the statements:

It should come as no surprise that U.S. equity-market investors have been handsomely rewarded thus far this decade, a period of time that roughly corresponds with the recovery from the financial crisis (the bottom came in March 2009, roughly 10 months before the start of the 2010s). The S&P 500 SPX, +0.49%  is up nearly 140% since the start of the decade, and more than 180% on a total-return basis. The Dow Jones Industrial Average DJIA, +0.56%  is up more than 130% over the same period.

Facts:
SPX - 140% starting from 2010 to 2018, total return 180%
DJIA - 130% starting from 2010 to 2018. 

Actionable Items

In order for me to be able to understand the article, I have to read two articles first on investopedia, first one is what is sharpe ratio, and second one is to understand risk-adjusted return.