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 individual stocks have performed against the broad S&P 500.

Step on up, West Pharmaceutical Services (NYSE: WST).         

West Pharmaceutical Services shares have roughly matched the S&P 500 over the last quarter-century:

Source: S&P Capital IQ.

Since 1987, shares have returned an average of 10.1% a year, compared with 9.7% a year for the S&P (both include dividends). One thousand dollars invested in the S&P in 1987 would be worth $19,200 today, and, naturally, about the same in West Pharmaceutical Services.

Dividends accounted for a lot of those gains. Compounded since 1987, dividends have made up about half of West Pharmaceutical Services' total returns. For the S&P, dividends account for 39% of total returns.

Now have a look at how West Pharmaceutical Services earnings compare with S&P 500 earnings:

Source: S&P Capital IQ.

Again, pretty average. Since 1995, West Pharmaceutical Services earnings per share have increased by 5.6% per year, compared with 6% a year for the broader index. 

What's that meant for valuations? West Pharmaceutical Services has traded for an average of 20 times earnings since 1987 -- below the 24 times earnings of the broader S&P 500.

Through it all, shares have been mediocre performers over the last quarter-century.  

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

Fool contributor Morgan Housel doesn't own shares in any of the companies mentioned in this article. Follow him on Twitter @TMFHousel. The Motley Fool has a disclosure policy. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days.