For each division in a race we do the following:
  
  Optimal Time (OT) = 1st Percentile Swim + 
                      1st Percentile T1 + 
                      1st Percentile Bike + 
                      1st Percentile T2 + 
                      1st Percentile Run
  
  Fastest Time (FT) = 1st Percentile Overall

                         OT + (2 * FT)
  Reference Time (RT) = ---------------
                               3

                      5th Percentile Time
  Scale (S) = ----------------------------------
               Median (or 50th Percentile) Time

  Time (T) = the athlete time we calculate the DPI for

  Adjusted Time (AT) = T - ((T - RT) * S * 0.5)


         100 * RT 
  DPI = ----------
            AT