Frequencies for first 10,000 rows of ccs variable in nhamcsopd2009 dataset :

     does this |
  clinic offer |
      cervical |
        cancer |
    screening? |      Freq.     Percent        Cum.
---------------+-----------------------------------
         blank |        316        3.16        3.16
       unknown |         89        0.89        4.05
not applicable |      4,790       47.90       51.95
           yes |      3,030       30.30       82.25
            no |      1,775       17.75      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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