Frequencies for first 10,000 rows of dmage variable in natl1972 dataset : Age of | Mother | Freq. Percent Cum. ------------+----------------------------------- 12 | 1 0.01 0.01 13 | 8 0.08 0.09 14 | 65 0.65 0.74 15 | 179 1.79 2.53 16 | 321 3.21 5.74 17 | 554 5.54 11.28 18 | 672 6.72 18.00 19 | 801 8.01 26.01 20 | 784 7.84 33.85 21 | 743 7.43 41.28 22 | 728 7.28 48.56 23 | 738 7.38 55.94 24 | 746 7.46 63.40 25 | 651 6.51 69.91 26 | 460 4.60 74.51 27 | 428 4.28 78.79 28 | 350 3.50 82.29 29 | 310 3.10 85.39 30 | 257 2.57 87.96 31 | 206 2.06 90.02 32 | 184 1.84 91.86 33 | 136 1.36 93.22 34 | 139 1.39 94.61 35 | 113 1.13 95.74 36 | 112 1.12 96.86 37 | 87 0.87 97.73 38 | 54 0.54 98.27 39 | 54 0.54 98.81 40 | 40 0.40 99.21 41 | 32 0.32 99.53 42 | 21 0.21 99.74 43 | 8 0.08 99.82 44 | 11 0.11 99.93 45 | 2 0.02 99.95 46 | 3 0.03 99.98 48 | 2 0.02 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 3 Jan 2016