Frequencies for first 10,000 rows of pre4000 variable in natl1994 dataset :

   Previous |
     infant |
4000+ grams |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         72        0.72        0.72
          2 |      9,881       98.81       99.53
          9 |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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