Frequencies for first 10,000 rows of incervix variable in natlterr2002 dataset :

Incompetent |
     cervix |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         58        0.58        0.58
          2 |      9,927       99.27       99.85
          8 |         14        0.14       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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