During his time as governor, Davis made education his top priority and California spent eight billion dollars more than was required under Proposition 98 during his first term. Under Davis, California, standardized test scores increased for five straight years. Davis signed the nation's first state law requiring automakers to limit auto emissions. Davis supported laws to ban assault weapons and is also credited with improving relations between California and Mexico. Davis began his tenure as governor with strong approval ratings but they declined as voters blamed him for the California electricity crisis, the California budget crisis that followed the bursting of the dot-com bubble, and the car tax.