Frequencies for first 10,000 rows of clingest variable in natlterr2002 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         20 |          1        0.01        0.01
         23 |          8        0.08        0.09
         24 |         12        0.12        0.21
         25 |         10        0.10        0.31
         26 |         17        0.17        0.48
         27 |          5        0.05        0.53
         28 |         22        0.22        0.75
         29 |         18        0.18        0.93
         30 |         30        0.30        1.23
         31 |         28        0.28        1.51
         32 |         78        0.78        2.29
         33 |         65        0.65        2.94
         34 |        162        1.62        4.56
         35 |        231        2.31        6.87
         36 |        611        6.11       12.98
         37 |      1,500       15.00       27.98
         38 |      2,765       27.65       55.63
         39 |      2,295       22.95       78.58
         40 |      1,815       18.15       96.73
         41 |        296        2.96       99.69
         42 |         26        0.26       99.95
         99 |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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