Frequencies for first 10,000 rows of circul variable in linkco1991us_num dataset :

      Other |
circulatory |
/respirator |
y anomalies |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        253        2.53        2.53
          2 |      9,474       94.74       97.27
          9 |        273        2.73      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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