Frequencies for first 10,000 rows of lung variable in natlterr1996 dataset :

   Acute or |
    chronic |
       lung |
    disease |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         35        0.35        0.35
          2 |      9,961       99.61       99.96
          9 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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