Frequencies for first 10,000 rows of proc5 variable in namcs2012 dataset :

   Write-in |
  procedure |
       code |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |      9,995       99.95       99.95
       8908 |          1        0.01       99.96
       9032 |          1        0.01       99.97
       9059 |          2        0.02       99.99
       9952 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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