Frequencies for first 10,000 rows of ume_vac variable in natl2005 dataset :

 Vacuum U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        256        2.56        2.56
          2 |      9,690       96.90       99.46
          9 |         54        0.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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