Frequencies for first 10,000 rows of proc6per variable in nhamcsopd1993 dataset :

 service #6 |
  performed |
 or ordered |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,993       99.93       99.93
          1 |          3        0.03       99.96
          2 |          3        0.03       99.99
          3 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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