Frequencies for first 10,000 rows of pre4000 variable in natl1992 dataset :

   Previous |
     infant |
4000+ grams |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         65        0.65        0.65
          2 |      9,909       99.09       99.74
          9 |         26        0.26      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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