This is right in percentage terms - but also worth noting that the UK produces 4.7 tonnes of co2 per capita vs USA's 14.4 metric tons per capita. i.e. taking y

This is right in percentage terms - but also worth noting that the UK produces 4.7 tonnes of co2 per capita vs USA's 14.4 metric tons per capita. i.e. taking your 8% and 3% figures along with the tonnes of co2 above would mean in raw CO2 terms, the USA is producing more tonnes of aviation carbon per capita (i.e. per person) than the UK. The UK would be at 2.6% if it consumed 'other carbon' at USA rates (i.e. 14.4 metric tons per capita), but it is 8% because it consumed 4.7 tonnes per capita.