Frequencies for first 10,000 rows of proc2per variable in namcs1993 dataset :

 service #2 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,189       91.89       91.89
          1 |        426        4.26       96.15
          2 |        311        3.11       99.26
          3 |         74        0.74      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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