Frequencies for first 10,000 rows of ip_chlam variable in natl2017 dataset :

Chlamydia Y |
        Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,682       96.82       96.82
          U |        107        1.07       97.89
          Y |        211        2.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Sep 2018