Investing isn't easy. Even Warren Buffett counsels that most investors should invest in a low-cost index like the S&P 500. That way, "you'll be buying into a wonderful industry, which in effect is all of American industry," he says.

But there are, of course, companies whose long-term fortunes differ substantially from the index. In this series, we look at how members of the S&P 500 have performed compared with the index itself.

Step on up, PPG Industries (NYSE: PPG).

PPG Industries shares have crushed the S&P 500 over the last three decades:

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Source: S&P Capital IQ.

Since 1980, shares returned an average of 15.1% a year, compared with 11.1% a year for the S&P (both include dividends). That difference adds up fast. One thousand dollars invested in the S&P in 1980 would be worth $29,400 today. In PPG Industries, it'd be worth $89,300.

Dividends accounted for a lot of those gains. Compounded since 1980, dividends have made up about two-third PPG Industries' total returns. For the S&P, dividends account for 41.5% of total returns.

Now have a look at how PPG Industries earnings compared with S&P 500 earnings:

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Source: S&P Capital IQ.

Perhaps surprising given shareholder returns, there's underperformance. Since 1995, earnings per share have grown by an average of 3.1% a year, compared with 6% a year for the broader index. The former's is about equal to the rate of inflation, or flat in "real" terms.

What's it all meant for valuations? PPG Industries has traded for an average of 16 times earnings since 1980 -- below the 21 times earnings for the broader S&P 500.

Through it all, PPG Industries shares have clearly been outperformers over the last three decades.  

Of course, the important question is whether that will continue. That's where you come in. Our CAPS community currently ranks PPG Industries with a five-star rating (out of five). Do you disagree? Leave your thoughts in the comment section below, or add PPG Industries to My Watchlist.