Frequencies for first 10,000 rows of circul variable in natl2000 dataset :

      Other |
circulatory |
/respirator |
y anomalies |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         16        0.16        0.16
          2 |      9,984       99.84      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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