Frequencies for first 10,000 rows of incervix variable in natlterr1998 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         33        0.33        0.33
          2 |      9,965       99.65       99.98
          9 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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