Frequencies for first 10,000 rows of incervix variable in natl1993 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         25        0.25        0.25
          2 |      9,953       99.53       99.78
          9 |         22        0.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015