Frequencies for first 10,000 rows of proc3per variable in nhamcsopd1994 dataset :

 service #3 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,626       96.26       96.26
          1 |        244        2.44       98.70
          2 |         93        0.93       99.63
          3 |         37        0.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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