Frequencies for first 10,000 rows of unkins variable in nhamcsed1995 dataset :

    unknown |
  insurance |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,590       95.90       95.90
          1 |        410        4.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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