Frequencies for first 10,000 rows of dmage variable in natl1994 dataset :

     Age of |
     Mother |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          3        0.03        0.03
         13 |         13        0.13        0.16
         14 |         55        0.55        0.71
         15 |        127        1.27        1.98
         16 |        231        2.31        4.29
         17 |        381        3.81        8.10
         18 |        443        4.43       12.53
         19 |        615        6.15       18.68
         20 |        645        6.45       25.13
         21 |        602        6.02       31.15
         22 |        675        6.75       37.90
         23 |        589        5.89       43.79
         24 |        586        5.86       49.65
         25 |        543        5.43       55.08
         26 |        529        5.29       60.37
         27 |        518        5.18       65.55
         28 |        503        5.03       70.58
         29 |        513        5.13       75.71
         30 |        418        4.18       79.89
         31 |        400        4.00       83.89
         32 |        346        3.46       87.35
         33 |        284        2.84       90.19
         34 |        235        2.35       92.54
         35 |        195        1.95       94.49
         36 |        182        1.82       96.31
         37 |        119        1.19       97.50
         38 |         92        0.92       98.42
         39 |         69        0.69       99.11
         40 |         39        0.39       99.50
         41 |         24        0.24       99.74
         42 |         19        0.19       99.93
         43 |          4        0.04       99.97
         44 |          2        0.02       99.99
         46 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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