Frequencies for first 10,000 rows of pre4000 variable in natl1993 dataset :

   Previous |
     infant |
4000+ grams |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         78        0.78        0.78
          2 |      9,900       99.00       99.78
          9 |         22        0.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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