Frequencies for first 10,000 rows of f_urf_hydra variable in natl2006 dataset :

Hydramnios/ |
Oligohydram |
       nios |
(urf_hydra) |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         13        0.13        0.13
          1 |      9,987       99.87      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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