Frequencies for first 10,000 rows of urf_incerv variable in natl2003 dataset :

Incompetent |
   cervix U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         20        0.20        0.20
          2 |      9,158       91.58       91.78
          8 |          7        0.07       91.85
          9 |        815        8.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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