Frequencies for first 10,000 rows of pre4000 variable in natlterr1996 dataset :

   Previous |
     infant |
4000+ grams |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          4        0.04        0.04
          2 |      9,992       99.92       99.96
          9 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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