Frequencies for first_yr variable in vehicle dataset :

      FIRST |
ACCIDENT-YE |
         AR |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        317       67.16       67.16
       2006 |         17        3.60       70.76
       2007 |         83       17.58       88.35
       2008 |         16        3.39       91.74
       9999 |         39        8.26      100.00
------------+-----------------------------------
      Total |        472      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016