Frequencies for first 10,000 rows of urf_incerv variable in natlterr2003 dataset :

Incompetent |
   cervix U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         80        0.80        0.80
          2 |      9,895       98.95       99.75
          8 |         23        0.23       99.98
          9 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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