Frequencies for first 10,000 rows of ucr65 variable in mort1975 dataset :

      ucr65 |      Freq.     Percent        Cum.
------------+-----------------------------------
         10 |      1,831       18.31       18.31
         20 |          8        0.08       18.39
         30 |        308        3.08       21.47
         40 |         46        0.46       21.93
         50 |      3,998       39.98       61.91
         80 |      3,809       38.09      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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