Frequencies for first 10,000 rows of clingest variable in natl1992 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          2        0.02        0.02
         19 |          2        0.02        0.04
         20 |          4        0.04        0.08
         21 |          7        0.07        0.15
         22 |          4        0.04        0.19
         23 |          7        0.07        0.26
         24 |          4        0.04        0.30
         25 |         17        0.17        0.47
         26 |         14        0.14        0.61
         27 |         14        0.14        0.75
         28 |         29        0.29        1.04
         29 |         17        0.17        1.21
         30 |         30        0.30        1.51
         31 |         29        0.29        1.80
         32 |         42        0.42        2.22
         33 |         89        0.89        3.11
         34 |        115        1.15        4.26
         35 |        165        1.65        5.91
         36 |        385        3.85        9.76
         37 |        622        6.22       15.98
         38 |      1,230       12.30       28.28
         39 |      2,101       21.01       49.29
         40 |      3,689       36.89       86.18
         41 |      1,049       10.49       96.67
         42 |        287        2.87       99.54
         43 |         25        0.25       99.79
         44 |          1        0.01       99.80
         99 |         20        0.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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