Frequencies for first 10,000 rows of urf_pre4000 variable in natl2005 dataset :

   Previous |
     infant |
4000+ Grams |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        418        4.18        4.18
          2 |      9,459       94.59       98.77
          9 |        123        1.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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