Frequencies for first 10,000 rows of urf_lung variable in natlterr2003 dataset :

   Acute or |
    Chronic |
       Lung |
  Disease U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         36        0.36        0.36
          2 |      9,939       99.39       99.75
          8 |         23        0.23       99.98
          9 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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