Frequencies for first 10,000 rows of dgestat variable in natl1979 dataset :

  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         20 |          5        0.05        0.05
         22 |          9        0.09        0.14
         23 |          6        0.06        0.20
         24 |          6        0.06        0.26
         25 |          6        0.06        0.32
         26 |         11        0.11        0.43
         27 |         10        0.10        0.53
         28 |         13        0.13        0.66
         29 |         21        0.21        0.87
         30 |         34        0.34        1.21
         31 |         36        0.36        1.57
         32 |         52        0.52        2.09
         33 |         75        0.75        2.84
         34 |        129        1.29        4.13
         35 |        191        1.91        6.04
         36 |        267        2.67        8.71
         37 |        457        4.57       13.28
         38 |        854        8.54       21.82
         39 |      1,511       15.11       36.93
         40 |      1,653       16.53       53.46
         41 |      1,257       12.57       66.03
         42 |        703        7.03       73.06
         43 |        318        3.18       76.24
         44 |        206        2.06       78.30
         45 |        107        1.07       79.37
         46 |         63        0.63       80.00
         47 |         25        0.25       80.25
         48 |         14        0.14       80.39
         49 |         16        0.16       80.55
         50 |         14        0.14       80.69
         51 |          7        0.07       80.76
         52 |          8        0.08       80.84
         99 |      1,916       19.16      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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