Frequencies for first 10,000 rows of proc7 variable in namcs2011 dataset :

Procedure 7 |
  - 4 digit |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |      9,992       99.92       99.92
       8913 |          2        0.02       99.94
       8938 |          2        0.02       99.96
       8959 |          3        0.03       99.99
       9201 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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