Frequencies for first 10,000 rows of proc7per variable in namcs1994 dataset :

 service #7 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,998       99.98       99.98
          2 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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