Frequencies for first 10,000 rows of f_clinest variable in natl2005 dataset :

   Clinical |
Estimate of |
  Gestation |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |          3        0.03        0.03
          1 |      9,997       99.97      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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