Frequencies for first 10,000 rows of proc7 variable in namcs1994 dataset :

 service #7 |
  procedure |
   code - 4 |
     digits |      Freq.     Percent        Cum.
------------+-----------------------------------
       0000 |      9,998       99.98       99.98
       8769 |          1        0.01       99.99
       8874 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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