Frequencies for first 10,000 rows of proc1per variable in nhamcsopd1994 dataset :

 service #1 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      6,302       63.02       63.02
          1 |      2,446       24.46       87.48
          2 |        921        9.21       96.69
          3 |        331        3.31      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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