Frequencies for first 10,000 rows of dmage variable in natl1995 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         13 |         12        0.12        0.12
         14 |         43        0.43        0.55
         15 |        105        1.05        1.60
         16 |        271        2.71        4.31
         17 |        364        3.64        7.95
         18 |        466        4.66       12.61
         19 |        601        6.01       18.62
         20 |        635        6.35       24.97
         21 |        568        5.68       30.65
         22 |        596        5.96       36.61
         23 |        621        6.21       42.82
         24 |        621        6.21       49.03
         25 |        601        6.01       55.04
         26 |        499        4.99       60.03
         27 |        504        5.04       65.07
         28 |        527        5.27       70.34
         29 |        510        5.10       75.44
         30 |        456        4.56       80.00
         31 |        387        3.87       83.87
         32 |        382        3.82       87.69
         33 |        273        2.73       90.42
         34 |        242        2.42       92.84
         35 |        189        1.89       94.73
         36 |        168        1.68       96.41
         37 |        120        1.20       97.61
         38 |         80        0.80       98.41
         39 |         51        0.51       98.92
         40 |         52        0.52       99.44
         41 |         28        0.28       99.72
         42 |          7        0.07       99.79
         43 |         10        0.10       99.89
         44 |          5        0.05       99.94
         45 |          2        0.02       99.96
         46 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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