Frequencies for first 10,000 rows of proc72d variable in namcs2013 dataset :

Procedure 7 |
  - 2 digit |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |      9,996       99.96       99.96
         13 |          1        0.01       99.97
         14 |          1        0.01       99.98
         57 |          1        0.01       99.99
         71 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 27 Mar 2017