Frequencies for first 10,000 rows of circul variable in natl1993 dataset :

      Other |
circulatory |
/respirator |
y anomalies |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          6        0.06        0.06
          2 |      9,994       99.94      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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