Frequencies for first 10,000 rows of birwt12 variable in natl1974 dataset :

Birthweight |
  Recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          4        0.04        0.04
          2 |         40        0.40        0.44
          3 |         70        0.70        1.14
          4 |        160        1.60        2.74
          5 |        516        5.16        7.90
          6 |      1,818       18.18       26.08
          7 |      3,751       37.51       63.59
          8 |      2,688       26.88       90.47
          9 |        763        7.63       98.10
         10 |        138        1.38       99.48
         11 |         26        0.26       99.74
         12 |         26        0.26      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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