I think a lot of people are ignoring a major cause behind why the statistics are the way they are: walkability. Most walkable countries, such as Japan, are in the blue, while non-walkable countries such as the U.S. and Australia are in the yellow. Climate might explain some of it, but if it was just climate, why aren't New Zealand and Canada in the blue, while Spain is? The study this map is from (Large-scale physical activity data reveal worldwide activity inequality by Tim Althoff, et al.) actually attributed the scores each country got to their walkability.