Frequencies for first 10,000 rows of cbc variable in nhamcsed2001 dataset :

        cbc |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      7,047       70.47       70.47
          1 |      2,953       29.53      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016