6% or ~500 lives per year according to this article (though it notes an increase in vehicle related deaths, so some of that may be cancelled by the additional road traffic) - https://qz.com/2038153/drunk-driving-deaths-dropped-as-more-...

Not a bad result, but probably not worth the problems that their current business model entails. There's clearly opportunities for better transportation options, they just need to make economic sense.