Frequencies for first 10,000 rows of dmage variable in natl1993 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          2        0.02        0.02
         13 |          8        0.08        0.10
         14 |         67        0.67        0.77
         15 |        137        1.37        2.14
         16 |        279        2.79        4.93
         17 |        356        3.56        8.49
         18 |        509        5.09       13.58
         19 |        606        6.06       19.64
         20 |        650        6.50       26.14
         21 |        706        7.06       33.20
         22 |        628        6.28       39.48
         23 |        567        5.67       45.15
         24 |        569        5.69       50.84
         25 |        532        5.32       56.16
         26 |        558        5.58       61.74
         27 |        496        4.96       66.70
         28 |        549        5.49       72.19
         29 |        471        4.71       76.90
         30 |        448        4.48       81.38
         31 |        382        3.82       85.20
         32 |        330        3.30       88.50
         33 |        255        2.55       91.05
         34 |        238        2.38       93.43
         35 |        173        1.73       95.16
         36 |        160        1.60       96.76
         37 |        111        1.11       97.87
         38 |         85        0.85       98.72
         39 |         46        0.46       99.18
         40 |         33        0.33       99.51
         41 |         19        0.19       99.70
         42 |         16        0.16       99.86
         43 |         10        0.10       99.96
         44 |          2        0.02       99.98
         45 |          1        0.01       99.99
         47 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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