Frequencies for first 10,000 rows of uop_monit variable in natl2005 dataset :

 Electronic |
      Fetal |
 Monitoring |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      7,040       70.40       70.40
          2 |      2,852       28.52       98.92
          9 |        108        1.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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