Frequencies for first 10,000 rows of unkins variable in nhamcsed1996 dataset :

    unknown |
  insurance |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,616       96.16       96.16
          1 |        384        3.84      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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