Frequencies for first 10,000 rows of dmage variable in natl2001 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         13 |          6        0.06        0.06
         14 |         28        0.28        0.34
         15 |         77        0.77        1.11
         16 |        156        1.56        2.67
         17 |        314        3.14        5.81
         18 |        423        4.23       10.04
         19 |        566        5.66       15.70
         20 |        677        6.77       22.47
         21 |        656        6.56       29.03
         22 |        651        6.51       35.54
         23 |        620        6.20       41.74
         24 |        592        5.92       47.66
         25 |        585        5.85       53.51
         26 |        532        5.32       58.83
         27 |        528        5.28       64.11
         28 |        473        4.73       68.84
         29 |        526        5.26       74.10
         30 |        476        4.76       78.86
         31 |        399        3.99       82.85
         32 |        316        3.16       86.01
         33 |        278        2.78       88.79
         34 |        239        2.39       91.18
         35 |        233        2.33       93.51
         36 |        191        1.91       95.42
         37 |        131        1.31       96.73
         38 |        105        1.05       97.78
         39 |         84        0.84       98.62
         40 |         47        0.47       99.09
         41 |         38        0.38       99.47
         42 |         22        0.22       99.69
         43 |         15        0.15       99.84
         44 |          8        0.08       99.92
         45 |          5        0.05       99.97
         46 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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