Frequencies for first 10,000 rows of urf_incerv variable in natl2005 dataset :

Incompetent |
   cervix U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         13        0.13        0.13
          2 |      9,864       98.64       98.77
          9 |        123        1.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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