Frequencies for first 10,000 rows of clingest variable in natl1991 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         19 |          2        0.02        0.02
         21 |          3        0.03        0.05
         22 |          2        0.02        0.07
         23 |          3        0.03        0.10
         24 |         10        0.10        0.20
         25 |         10        0.10        0.30
         26 |         13        0.13        0.43
         27 |         13        0.13        0.56
         28 |         22        0.22        0.78
         29 |         14        0.14        0.92
         30 |         25        0.25        1.17
         31 |         40        0.40        1.57
         32 |         59        0.59        2.16
         33 |         53        0.53        2.69
         34 |        123        1.23        3.92
         35 |        156        1.56        5.48
         36 |        352        3.52        9.00
         37 |        597        5.97       14.97
         38 |      1,307       13.07       28.04
         39 |      1,889       18.89       46.93
         40 |      3,696       36.96       83.89
         41 |      1,203       12.03       95.92
         42 |        348        3.48       99.40
         43 |         21        0.21       99.61
         44 |          4        0.04       99.65
         45 |          2        0.02       99.67
         99 |         33        0.33      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015