Frequencies for first 10,000 rows of dmage variable in natl1991 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          1        0.01        0.01
         13 |          3        0.03        0.04
         14 |         34        0.34        0.38
         15 |         80        0.80        1.18
         16 |        235        2.35        3.53
         17 |        362        3.62        7.15
         18 |        512        5.12       12.27
         19 |        633        6.33       18.60
         20 |        665        6.65       25.25
         21 |        614        6.14       31.39
         22 |        611        6.11       37.50
         23 |        576        5.76       43.26
         24 |        608        6.08       49.34
         25 |        582        5.82       55.16
         26 |        623        6.23       61.39
         27 |        571        5.71       67.10
         28 |        531        5.31       72.41
         29 |        482        4.82       77.23
         30 |        451        4.51       81.74
         31 |        398        3.98       85.72
         32 |        333        3.33       89.05
         33 |        266        2.66       91.71
         34 |        228        2.28       93.99
         35 |        155        1.55       95.54
         36 |        147        1.47       97.01
         37 |        101        1.01       98.02
         38 |         69        0.69       98.71
         39 |         53        0.53       99.24
         40 |         28        0.28       99.52
         41 |         22        0.22       99.74
         42 |         18        0.18       99.92
         43 |          2        0.02       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