Frequencies for first 10,000 rows of ip_chlam variable in natl2014 dataset :

Chlamydia Y |
        Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,542       95.42       95.42
          U |        169        1.69       97.11
          Y |        289        2.89      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016