Your statement is odd since in the years before the law change, deaths were relatively constant at around 175 per year. In the year it passed it spiked to about 250 (1/2 year with law change) and went to about 300 then first full year after. It then continued up to over 500 deaths per year.
In FL there was a radical miami doctor who was caught makeing fraudulant stats regarding deaths. The local state rights groups had those corrected long ago.
You also have to account for the fact that since the change in law, motorcycle ownership has nearly doubled and is continuing to grow. PS they also count the explosion of scooters in the motorcycle injury stats and those were almost non-existent 10 years ago.