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

  Prolonged |
      labor |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         38        0.38        0.38
          2 |      9,916       99.16       99.54
          9 |         46        0.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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