Frequencies for first 10,000 rows of proc3per variable in namcs1994 dataset :

 service #3 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,770       97.70       97.70
          1 |        101        1.01       98.71
          2 |        100        1.00       99.71
          3 |         29        0.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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