Frequencies for ptype variable in impact2007 dataset :

   Provider |
       Type |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,824       76.80       76.80
          7 |        187        5.09       81.89
          8 |         36        0.98       82.87
         14 |        146        3.97       86.84
         15 |          8        0.22       87.05
         16 |        374       10.17       97.23
         17 |         98        2.67       99.89
         21 |          3        0.08       99.97
       9999 |          1        0.03      100.00
------------+-----------------------------------
      Total |      3,677      100.00

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