Frequencies for first 10,000 rows of proc2per variable in namcs1994 dataset :

 service #2 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,171       91.71       91.71
          1 |        422        4.22       95.93
          2 |        304        3.04       98.97
          3 |        103        1.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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