Frequencies for first 10,000 rows of urf_hydra variable in natlterr2006 dataset :

Hydramnios/ |
Oligohydram |
   nios RFP |
686=f_urf_h |
     ydra U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         22        0.22        0.22
          2 |      4,774       47.74       47.96
          9 |      1,479       14.79       62.75
          . |      3,725       37.25      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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