Which plot to use for data spanned on multiple years?
For time data, you should often use a simple Line Chart, with time on the X axis and the other variable dependent of time (here the number of accident) on the Y axis. Since you have several states to plot, you can simply draw one line for each state. to differentiate them, you can use a visualization variable : color, width, pattern ... Color is probably the most relevant here. You can as well write the name of the state near each line.