I aske earlier if anyone knew of any 'official' stats on what proportion of people are runners.... perhaps from a sizeable survey. Since asking the question, I got a bit interested and googled... but didn't find much.
As I type, I wonder if any of the shoe manufacturers' sites might have anything...
... Anyone know anything?
I doubt if there are any stats. Just because you buy running shoes doesn't make you a runner, you might just like the shoes.
Also, many runners have more than one style of running shoe at a time (road and trail, for example), and more than one pair on the go.
UK Athletics will have the data of people who are competing members of affiliated clubs, but that by no means includes all people who run.