Frequencies for first 10,000 rows of dmage variable in natlterr1999 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         13 |         14        0.14        0.14
         14 |         58        0.58        0.72
         15 |        131        1.31        2.03
         16 |        276        2.76        4.79
         17 |        388        3.88        8.67
         18 |        549        5.49       14.16
         19 |        642        6.42       20.58
         20 |        649        6.49       27.07
         21 |        701        7.01       34.08
         22 |        621        6.21       40.29
         23 |        649        6.49       46.78
         24 |        578        5.78       52.56
         25 |        540        5.40       57.96
         26 |        544        5.44       63.40
         27 |        496        4.96       68.36
         28 |        486        4.86       73.22
         29 |        395        3.95       77.17
         30 |        379        3.79       80.96
         31 |        326        3.26       84.22
         32 |        301        3.01       87.23
         33 |        273        2.73       89.96
         34 |        234        2.34       92.30
         35 |        189        1.89       94.19
         36 |        154        1.54       95.73
         37 |        124        1.24       96.97
         38 |         98        0.98       97.95
         39 |         79        0.79       98.74
         40 |         56        0.56       99.30
         41 |         27        0.27       99.57
         42 |         18        0.18       99.75
         43 |         14        0.14       99.89
         44 |          7        0.07       99.96
         45 |          1        0.01       99.97
         46 |          2        0.02       99.99
         47 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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