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

Hydrocephal |
         us |
(uca_hydro) |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      5,186       51.86       51.86
          1 |      4,814       48.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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