Frequencies for first 10,000 rows of lung variable in natl1996 dataset :

   Acute or |
    chronic |
       lung |
    disease |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         86        0.86        0.86
          2 |      9,886       98.86       99.72
          9 |         28        0.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015