Frequencies for first 10,000 rows of incervix variable in natlterr1996 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         30        0.30        0.30
          2 |      9,966       99.66       99.96
          9 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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