Frequencies for first 10,000 rows of urf_pre4000 variable in natlterr2003 dataset :

   Previous |
     infant |
4000+ Grams |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         17        0.17        0.17
          2 |      9,958       99.58       99.75
          8 |         23        0.23       99.98
          9 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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