Frequencies for first 10,000 rows of dmage variable in natl1985 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         13 |          7        0.07        0.07
         14 |         46        0.46        0.53
         15 |        126        1.26        1.79
         16 |        216        2.16        3.95
         17 |        346        3.46        7.41
         18 |        539        5.39       12.80
         19 |        614        6.14       18.94
         20 |        661        6.61       25.55
         21 |        723        7.23       32.78
         22 |        670        6.70       39.48
         23 |        669        6.69       46.17
         24 |        734        7.34       53.51
         25 |        620        6.20       59.71
         26 |        621        6.21       65.92
         27 |        572        5.72       71.64
         28 |        527        5.27       76.91
         29 |        436        4.36       81.27
         30 |        418        4.18       85.45
         31 |        335        3.35       88.80
         32 |        274        2.74       91.54
         33 |        232        2.32       93.86
         34 |        155        1.55       95.41
         35 |        119        1.19       96.60
         36 |        108        1.08       97.68
         37 |         83        0.83       98.51
         38 |         55        0.55       99.06
         39 |         38        0.38       99.44
         40 |         30        0.30       99.74
         41 |         13        0.13       99.87
         42 |          5        0.05       99.92
         43 |          3        0.03       99.95
         44 |          2        0.02       99.97
         45 |          2        0.02       99.99
         49 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016