Frequencies for first 10,000 rows of hmo variable in nhamcsopd1998 dataset :

       does |
    patient |
  belong to |
    an hmo? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,618       26.18       26.18
          2 |      5,372       53.72       79.90
          3 |      1,906       19.06       98.96
          4 |        104        1.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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