The remaining 98.3% comes from adverts plastered over phone box windows.

Probably.

Phone boxes...

1) When did you last use one?
1b) What for?
2) i) How far is the nearest one from your home?
2) ii) ...from your work/school/jobcentreplus?
3) What is the minimum charge for a call these days?
4) Something about calling cards.
5) Something about non-BT ones.
6) I bet some prick has claimed that hipsters have ditched mobile phones and reverted to phone boxes.
7) AOB?