Frequencies for first 10,000 rows of vacuum variable in natl1994 dataset :

     Vacuum |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        483        4.83        4.83
          2 |      9,495       94.95       99.78
          9 |         22        0.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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