Code:
   Cohort |      Freq.     Percent        Cum.
------------+-----------------------------------
         -2 |      5,245       15.43       15.43
         -4 |      6,325       18.61       34.04
         -6 |      6,478       19.06       53.10
          0 |      4,371       12.86       65.96
          6 |      4,244       12.49       78.45
          8 |      7,325       21.55      100.00
------------+-----------------------------------
      Total |     33,988      100.00