Frequencies for first 10,000 rows of incervix variable in natl1998 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         21        0.21        0.21
          2 |      9,979       99.79      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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