Frequencies for first 10,000 rows of hydra variable in natl1992 dataset :

Hydramnios/ |
Oligohydram |
       nios |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         79        0.79        0.79
          2 |      9,895       98.95       99.74
          9 |         26        0.26      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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