A stock's price movement over the past year as compared to a market index (the S&P 500).
Value below 1.0 means the stock shows relative weakness in price movement (underperformed the market); a
value above 1.0 means the stock shows relative strength over the 1-year period. Equation for Relative
Strength: [current stock price/year-ago stock price] [current S&P 500/year-ago S&P 500]