@peterdutoit interesting study. A pity that the raw data for that chart is not accessible (that I could see).

e.g. I infer that, at 3.6% of 3.9GT, the UK’s outbound tourism amounts to ~140 MT, but that must be just the blue bit, so the grey domestic bit can only be guessed at. But that assessment doesn’t look quite right relative to the x-axis.

It would be better if the grey bit was integrated with both blue and green in a single chart and that the data is inspectable.