Frequencies for first 10,000 rows of dmage variable in natl1998 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         11 |          1        0.01        0.01
         12 |          2        0.02        0.03
         13 |         12        0.12        0.15
         14 |         34        0.34        0.49
         15 |         93        0.93        1.42
         16 |        220        2.20        3.62
         17 |        354        3.54        7.16
         18 |        519        5.19       12.35
         19 |        592        5.92       18.27
         20 |        629        6.29       24.56
         21 |        630        6.30       30.86
         22 |        638        6.38       37.24
         23 |        581        5.81       43.05
         24 |        594        5.94       48.99
         25 |        572        5.72       54.71
         26 |        601        6.01       60.72
         27 |        560        5.60       66.32
         28 |        529        5.29       71.61
         29 |        412        4.12       75.73
         30 |        365        3.65       79.38
         31 |        345        3.45       82.83
         32 |        355        3.55       86.38
         33 |        268        2.68       89.06
         34 |        258        2.58       91.64
         35 |        202        2.02       93.66
         36 |        173        1.73       95.39
         37 |        141        1.41       96.80
         38 |         91        0.91       97.71
         39 |         91        0.91       98.62
         40 |         52        0.52       99.14
         41 |         33        0.33       99.47
         42 |         21        0.21       99.68
         43 |         18        0.18       99.86
         44 |          9        0.09       99.95
         45 |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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