These figures slightly surprise me. Aren't United always the best seller?
Just goes to show you need continued success.
At the risk of sounding very Brexit, the foreign fans aren't always "for life" they just like football and the alure of the Premier League, if you fall off they don't want to suffer weekly so they swap allegiance to the successful/attractive team, we are one of those at the moment that are doing well and are fun to watch, United have fallen off that bandwagon.
Also shows in City's numbers, a nothing team that used dirty money to achieve what they have now, but those million shirts they sell outside the UK is because they are currently fashionable, I wonder how many City shirts sold in, lets say their Middle Eastern audiences 20 years ago.