A great way to measure a stock's performance is to check its Relative Strength line vs. the S&P 500. IBD's Screen Of The Day is Bolting RS Lines. It lists top-rated stocks by IBD Relative Strength Rating, sorted for the five whose RS is accelerating at the fastest rate. Here are the top five companies on the list: Packaging Corp. of America (PKG), SEIC Investment (SEIC), Google (GOOG), Gilead Sciences (GILD) and Calumet Sciences (CLMT). They fell