Frequencies for first 10,000 rows of dmage variable in natl1992 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          2        0.02        0.02
         13 |          8        0.08        0.10
         14 |         47        0.47        0.57
         15 |         95        0.95        1.52
         16 |        196        1.96        3.48
         17 |        310        3.10        6.58
         18 |        475        4.75       11.33
         19 |        616        6.16       17.49
         20 |        638        6.38       23.87
         21 |        704        7.04       30.91
         22 |        631        6.31       37.22
         23 |        565        5.65       42.87
         24 |        564        5.64       48.51
         25 |        588        5.88       54.39
         26 |        582        5.82       60.21
         27 |        568        5.68       65.89
         28 |        557        5.57       71.46
         29 |        504        5.04       76.50
         30 |        464        4.64       81.14
         31 |        395        3.95       85.09
         32 |        312        3.12       88.21
         33 |        293        2.93       91.14
         34 |        249        2.49       93.63
         35 |        174        1.74       95.37
         36 |        143        1.43       96.80
         37 |        109        1.09       97.89
         38 |         76        0.76       98.65
         39 |         56        0.56       99.21
         40 |         31        0.31       99.52
         41 |         24        0.24       99.76
         42 |          8        0.08       99.84
         43 |         10        0.10       99.94
         44 |          4        0.04       99.98
         46 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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