Frequencies for first 10,000 rows of dmage variable in natl2002 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         13 |          3        0.03        0.03
         14 |         13        0.13        0.16
         15 |         38        0.38        0.54
         16 |        100        1.00        1.54
         17 |        189        1.89        3.43
         18 |        302        3.02        6.45
         19 |        465        4.65       11.10
         20 |        516        5.16       16.26
         21 |        566        5.66       21.92
         22 |        627        6.27       28.19
         23 |        574        5.74       33.93
         24 |        571        5.71       39.64
         25 |        563        5.63       45.27
         26 |        538        5.38       50.65
         27 |        555        5.55       56.20
         28 |        513        5.13       61.33
         29 |        461        4.61       65.94
         30 |        497        4.97       70.91
         31 |        460        4.60       75.51
         32 |        421        4.21       79.72
         33 |        360        3.60       83.32
         34 |        326        3.26       86.58
         35 |        273        2.73       89.31
         36 |        282        2.82       92.13
         37 |        193        1.93       94.06
         38 |        166        1.66       95.72
         39 |        128        1.28       97.00
         40 |        100        1.00       98.00
         41 |         68        0.68       98.68
         42 |         59        0.59       99.27
         43 |         38        0.38       99.65
         44 |         25        0.25       99.90
         45 |          5        0.05       99.95
         46 |          2        0.02       99.97
         47 |          2        0.02       99.99
         49 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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