Frequencies for first 10,000 rows of ym variable in morg07 dataset :

time series |
   month of |
      first |
month-in-sa |
       mple |      Freq.     Percent        Cum.
------------+-----------------------------------
        549 |      5,024       50.24       50.24
        561 |      4,976       49.76      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Mar 2017