Frequencies for first 10,000 rows of proc4per variable in nhamcsopd1994 dataset :

 service #4 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,892       98.92       98.92
          1 |         74        0.74       99.66
          2 |         22        0.22       99.88
          3 |         12        0.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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