Frequencies for first 10,000 rows of ven30m variable in linkco1991us_num dataset :

   Assisted |
ventilation |
       - 30 |
 minutes or |
       more |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        839        8.39        8.39
          2 |      8,010       80.10       88.49
          8 |         10        0.10       88.59
          9 |      1,141       11.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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