Frequencies for first 10,000 rows of proc72d variable in namcs2011 dataset :

Procedure 7 |
  - 2 digit |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |      9,992       99.92       99.92
         89 |          7        0.07       99.99
         92 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016