Not meant to refute the GP argument but, in the US at the federal level the AvGas tax per gallon and gasoline tax per gallon are about the same ~ $0.19. This is probably one of those areas where subsidies and such obfuscate the reality.
Well, here in Illinois, a gallon of diesel fuel is 85 cents per gallon. An international flight to Hong Kong will take a little over 40,000 gallons (but is tax exempt), so 34000 dollars worth of taxes are not paid per flight.
Jet fuel isn't tax exempt - there are both federal and state taxes to be paid on it
International fuel is tax exempt.
I can find no data on that, and transoceanic flight have to fuel up at takeoff airport thus can't exploit lower taxes at home hub (commonly done with shorter range flights).
You don't need data, it simply is exempt and has been since 1947.
I used to fuel commercial flights in a previous and much better life. International jets used a special ticket that said INTL EXEMPT on them.