Frequencies for first 10,000 rows of birwt12 variable in natl1970 dataset :

Birthweight |
  Recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          2        0.02        0.02
          2 |         39        0.39        0.41
          3 |         87        0.87        1.28
          4 |        150        1.50        2.78
          5 |        554        5.54        8.32
          6 |      1,857       18.57       26.89
          7 |      3,766       37.66       64.55
          8 |      2,544       25.44       89.99
          9 |        737        7.37       97.36
         10 |        158        1.58       98.94
         11 |         29        0.29       99.23
         12 |         77        0.77      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016