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

Hydrocephal |
     us RFP |
754=f_uca_h |
     ydro U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          1        0.01        0.01
          2 |      9,851       98.51       98.52
          9 |        148        1.48      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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