Frequencies for ptype variable in impact2002 dataset :

   Provider |
       Type |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      3,503       71.69       71.69
          7 |        213        4.36       76.05
          8 |         43        0.88       76.93
         14 |        333        6.82       83.75
         16 |        712       14.57       98.32
         17 |         77        1.58       99.90
         21 |          5        0.10      100.00
------------+-----------------------------------
      Total |      4,886      100.00

by Jean Roth , jroth@nber.org , 17 Mar 2016