I was also surprised because of my higher than USA average. I hadn't thought about (if I understand you correctly) people who live in a less urban area, and don't have a mass transit system available - the rating does assume we are all urban. The bulk of the population does live in an urban setting, but clearly the footprint system should take greater note of what is possible for rural participants. So, I am planning to take our large city mass transit more frequently.
We work away at these challenges as we individually can. Thanks for participating!