OK I did a little searching. In the first link, the article notes what you said but also states that those relationships have changed from that time to now
https://www.sciencedaily.com/releases/2009/09/090928172530.htm
And this article notes that it was mostly a lack of automobile deaths responsible for the change...since people couldnt afford cars
https://www.sciencedaily.com/releases/2011/03/110324202055.htm