Frequencies for first 10,000 rows of sch_bus variable in person dataset :

  SCHOOLBUS |
    RELATED |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,960       99.60       99.60
          1 |         40        0.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016