Frequencies for first 10,000 rows of dmage variable in natlterr1997 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          1        0.01        0.01
         13 |          9        0.09        0.10
         14 |         59        0.59        0.69
         15 |        162        1.62        2.31
         16 |        325        3.25        5.56
         17 |        453        4.53       10.09
         18 |        523        5.23       15.32
         19 |        665        6.65       21.97
         20 |        622        6.22       28.19
         21 |        637        6.37       34.56
         22 |        626        6.26       40.82
         23 |        602        6.02       46.84
         24 |        593        5.93       52.77
         25 |        571        5.71       58.48
         26 |        576        5.76       64.24
         27 |        503        5.03       69.27
         28 |        441        4.41       73.68
         29 |        384        3.84       77.52
         30 |        414        4.14       81.66
         31 |        352        3.52       85.18
         32 |        287        2.87       88.05
         33 |        265        2.65       90.70
         34 |        244        2.44       93.14
         35 |        165        1.65       94.79
         36 |        133        1.33       96.12
         37 |        107        1.07       97.19
         38 |         77        0.77       97.96
         39 |         63        0.63       98.59
         40 |         50        0.50       99.09
         41 |         44        0.44       99.53
         42 |         19        0.19       99.72
         43 |         10        0.10       99.82
         44 |         10        0.10       99.92
         45 |          7        0.07       99.99
         46 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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