performance graph the following graph compares the total return , assuming reinvestment of dividends , on an investment in the company , based on performance of the company's common stock , with the total return of the standard & poor's 500 composite stock index and the dow jones united states travel and leisure index for a five year period by measuring the changes in common stock prices from december 31 , 2012 to december 31 , 2017. .
the stock performance graph assumes for comparison that the value of the company's common stock and of each index was $ 100 on december 31 , 2012 and that all dividends were reinvested . past performance is not necessarily an indicator of future results. .
12/12 12/13 12/14 12/15 12/16 12/17
Royal Caribbean Cruises Ltd. 100.00 142.11 251.44 313.65 260.04 385.47
S&P 500 100.00 132.39 150.51 152.59 170.84 208.14
Dow Jones US Travel & Leisure 100.00 145.48 169.28 179.27 192.85 238.77
12/12 12/13 12/14 12/15 12/16 12/17
royal caribbean cruises ltd . 100.00 142.11 251.44 313.65 260.04 385.47
s&p 500 100.00 132.39 150.51 152.59 170.84 208.14
dow jones us travel & leisure 100.00 145.48 169.28 179.27 192.85 238.77
what is the mathematical mean for all three investments as of dec 31 , 2017?