Frequencies for first 10,000 rows of dgestat variable in natl1978 dataset :

  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         17 |          2        0.02        0.02
         18 |          1        0.01        0.03
         19 |          2        0.02        0.05
         20 |          1        0.01        0.06
         21 |          1        0.01        0.07
         22 |          4        0.04        0.11
         23 |          3        0.03        0.14
         24 |          3        0.03        0.17
         25 |          4        0.04        0.21
         26 |         10        0.10        0.31
         27 |         14        0.14        0.45
         28 |         22        0.22        0.67
         29 |         16        0.16        0.83
         30 |         19        0.19        1.02
         31 |         45        0.45        1.47
         32 |         54        0.54        2.01
         33 |         74        0.74        2.75
         34 |        104        1.04        3.79
         35 |        167        1.67        5.46
         36 |        316        3.16        8.62
         37 |        481        4.81       13.43
         38 |        836        8.36       21.79
         39 |      1,534       15.34       37.13
         40 |      1,642       16.42       53.55
         41 |      1,197       11.97       65.52
         42 |        647        6.47       71.99
         43 |        346        3.46       75.45
         44 |        208        2.08       77.53
         45 |        112        1.12       78.65
         46 |         54        0.54       79.19
         47 |         36        0.36       79.55
         48 |         16        0.16       79.71
         49 |          9        0.09       79.80
         50 |          7        0.07       79.87
         51 |          8        0.08       79.95
         52 |          4        0.04       79.99
         99 |      2,001       20.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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