I liked this form the Tax Justice Network:
The full report is here.
Note however two things.
The first is that the UK is not the biggest loser. Indeed, we're part of the problem.
And second, note that in the grand scale of things corporate tax abuse is not the biggest part of the tax gap. That biggest part is domestic tax evasion, largely by smaller companies and businesses, which outstrips tax avoidance in total by a ratio of at last 5 to 1, which is something tax campaigners will not give enough attention to because it does not attract headlines like this does.