what is the rate of return on an investment in advance auto parts from 2015 to 2016?
stock price performance the following graph shows a comparison of the cumulative total return on our common stock , the standard & poor 2019s 500 index and the standard & poor 2019s retail index . the graph assumes that the value of an investment in our common stock and in each such index was $ 100 on december 31 , 2011 , and that any dividends have been reinvested . the comparison in the graph below is based solely on historical data and is not intended to forecast the possible future performance of our common stock . comparison of cumulative total return among advance auto parts , inc. , s&p 500 index and s&p retail index company/index december 31 , december 29 , december 28 , january 3 , january 2 , december 31 .

| Company/Index | December 31, 2011 | December 29, 2012 | December 28, 2013 | January 3, 2015 | January 2, 2016 | December 31, 2016 |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| Advance Auto Parts | $100.00 | $102.87 | $158.46 | $228.88 | $217.49 | $244.64 |
| S&P 500 Index | 100.00 | 114.07 | 152.98 | 174.56 | 177.01 | 198.18 |
| S&P Retail Index | 100.00 | 122.23 | 178.55 | 196.06 | 245.31 | 256.69 |

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price_2015 = 228.88
price_2016 = 217.49
increase = price_2016 - price_2015
percent_increase = increase / price_2015
answer = percent_increase * 100