Frequencies for first 10,000 rows of incervix variable in natl1996 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         16        0.16        0.16
          2 |      9,956       99.56       99.72
          9 |         28        0.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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