Frequencies for first 10,000 rows of lung variable in linkco1991us_num dataset :

   Acute or |
    chronic |
       lung |
    disease |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         22        0.22        0.22
          2 |      9,698       96.98       97.20
          9 |        280        2.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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