Frequencies for first 10,000 rows of dmage variable in natl1986 dataset : Age of | Mother | Freq. Percent Cum. ------------+----------------------------------- 12 | 1 0.01 0.01 13 | 11 0.11 0.12 14 | 39 0.39 0.51 15 | 126 1.26 1.77 16 | 226 2.26 4.03 17 | 364 3.64 7.67 18 | 520 5.20 12.87 19 | 599 5.99 18.86 20 | 662 6.62 25.48 21 | 656 6.56 32.04 22 | 628 6.28 38.32 23 | 658 6.58 44.90 24 | 686 6.86 51.76 25 | 652 6.52 58.28 26 | 613 6.13 64.41 27 | 554 5.54 69.95 28 | 539 5.39 75.34 29 | 462 4.62 79.96 30 | 400 4.00 83.96 31 | 373 3.73 87.69 32 | 294 2.94 90.63 33 | 233 2.33 92.96 34 | 202 2.02 94.98 35 | 156 1.56 96.54 36 | 118 1.18 97.72 37 | 69 0.69 98.41 38 | 54 0.54 98.95 39 | 46 0.46 99.41 40 | 28 0.28 99.69 41 | 11 0.11 99.80 42 | 8 0.08 99.88 43 | 7 0.07 99.95 44 | 2 0.02 99.97 45 | 1 0.01 99.98 46 | 1 0.01 99.99 47 | 1 0.01 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 3 Jan 2016