Frequencies for first 10,000 rows of prolong variable in natl2001 dataset :

  Prolonged |
 labor (>20 |
     hours) |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         34        0.34        0.34
          2 |      9,964       99.64       99.98
          8 |          1        0.01       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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