Please define which ranges of dates you are talking about. The first time politician worried about road safety enough to pass a law was in 1903. Are you claiming that number were declining before 1903? Or are you referring to larger scale efforts, like national road safety acts in the USA? That would be 1966 (which is the exact date the current downward trend began, FWIW). Or do you have another time range in mind for "before politicians did anything about road safety."