Frequencies for first 10,000 rows of incervix variable in natl1994 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         17        0.17        0.17
          2 |      9,936       99.36       99.53
          9 |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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