Frequencies for first 10,000 rows of dmage variable in natl1976 dataset : Age of | Mother | Freq. Percent Cum. ------------+----------------------------------- 12 | 5 0.05 0.05 13 | 16 0.16 0.21 14 | 60 0.60 0.81 15 | 193 1.93 2.74 16 | 356 3.56 6.30 17 | 603 6.03 12.33 18 | 660 6.60 18.93 19 | 761 7.61 26.54 20 | 773 7.73 34.27 21 | 742 7.42 41.69 22 | 692 6.92 48.61 23 | 679 6.79 55.40 24 | 608 6.08 61.48 25 | 589 5.89 67.37 26 | 586 5.86 73.23 27 | 481 4.81 78.04 28 | 445 4.45 82.49 29 | 376 3.76 86.25 30 | 298 2.98 89.23 31 | 212 2.12 91.35 32 | 172 1.72 93.07 33 | 171 1.71 94.78 34 | 110 1.10 95.88 35 | 88 0.88 96.76 36 | 81 0.81 97.57 37 | 66 0.66 98.23 38 | 56 0.56 98.79 39 | 44 0.44 99.23 40 | 17 0.17 99.40 41 | 26 0.26 99.66 42 | 11 0.11 99.77 43 | 12 0.12 99.89 44 | 5 0.05 99.94 45 | 4 0.04 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