Frequencies for first 10,000 rows of year variable in dcracesingleages dataset :

       Year |      Freq.     Percent        Cum.
------------+-----------------------------------
       1990 |      1,257       12.57       12.57
       1991 |      1,261       12.61       25.18
       1992 |      1,262       12.62       37.80
       1993 |      1,268       12.68       50.48
       1994 |      1,270       12.70       63.18
       1995 |      1,264       12.64       75.82
       1996 |      1,253       12.53       88.35
       1997 |      1,165       11.65      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 2 Jan 2018