You'll find a table here (scroll down) showing the percentage of fans of Premier League teams who live in the same postcode as their home stadium. No prizes for guessing the club at the bottom of that table. However, note this:
Rightmove also broke down the data by city to reveal the level of support for Premiership clubs in the UK's hotbeds of football. In Manchester, although just 9% of Manchester United's fans live in the same postcode district as Old Trafford, the sheer scale of their support means that more than half of football fans in the city support United overall.
Heh. It's always [irony]puzzled me[/irony] why, coming away from the ground, I hear so many accents of Manchester and thereabouts. (Thanks: Pat M.)