Figures 2.01 and 2.02 reflect the trends in rates of persons injured and killed in crashes per 100 million vehicle miles traveled (MVMT)  from 1967 to 1997.  The injury rates were highest in the mid-seventies.  The rate of persons killed has markedly decreased from 5.2 persons killed per 100 MVMT  in 1968 to 1.8 persons killed per 100 MVMT in 1997.  The biggest decrease in fatalities occurred after the implementation of a 55 MPH speed limit in 1973.