Frequencies for first 10,000 rows of dmage variable in natlterr1994 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          3        0.03        0.03
         13 |         10        0.10        0.13
         14 |         62        0.62        0.75
         15 |        152        1.52        2.27
         16 |        322        3.22        5.49
         17 |        440        4.40        9.89
         18 |        520        5.20       15.09
         19 |        573        5.73       20.82
         20 |        621        6.21       27.03
         21 |        662        6.62       33.65
         22 |        639        6.39       40.04
         23 |        643        6.43       46.47
         24 |        611        6.11       52.58
         25 |        588        5.88       58.46
         26 |        541        5.41       63.87
         27 |        535        5.35       69.22
         28 |        494        4.94       74.16
         29 |        439        4.39       78.55
         30 |        391        3.91       82.46
         31 |        365        3.65       86.11
         32 |        266        2.66       88.77
         33 |        226        2.26       91.03
         34 |        191        1.91       92.94
         35 |        186        1.86       94.80
         36 |        151        1.51       96.31
         37 |        115        1.15       97.46
         38 |         82        0.82       98.28
         39 |         66        0.66       98.94
         40 |         31        0.31       99.25
         41 |         29        0.29       99.54
         42 |         26        0.26       99.80
         43 |          9        0.09       99.89
         44 |          9        0.09       99.98
         46 |          1        0.01       99.99
         48 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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