Frequencies for first 10,000 rows of proc2 variable in nhamcsed1995 dataset :

      other |
  procedure |
         #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
       0000 |      9,997       99.97       99.97
       8937 |          1        0.01       99.98
       9826 |          1        0.01       99.99
       9999 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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