Frequencies for first 10,000 rows of prolong variable in natl2002 dataset :

  Prolonged |
 labor (>20 |
     hours) |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        105        1.05        1.05
          2 |      9,596       95.96       97.01
          9 |        299        2.99      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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