Frequencies for pbszone variable in pbtype dataset :

School Zone |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      4,964       92.34       92.34
          1 |         25        0.47       92.80
          9 |        387        7.20      100.00
------------+-----------------------------------
      Total |      5,376      100.00

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