Frequencies for first 10,000 rows of uop_monit variable in natl2006 dataset :

 Electronic |
      Fetal |
 Monitoring |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      6,650       66.50       66.50
          2 |      3,216       32.16       98.66
          9 |        134        1.34      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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