How much fuel gets dumped and why? WRT Would the Aeroflot Flight 1492 have been able to dump its fuel first before landing?, I am wondering how much fuel gets dumped every year? gallons? litres? pounds?

Also, is it only in unplanned or emergency situations?
While according to British Airways estimates quoted in the Inter-Governmental Panel on Climate Change (IPPC) report on “Aviation and the Global Atmosphere” published in 1999 “only a very small percentage (on the order of 0.01%) of fuel used by the aviation industry each year is jettisoned”

https://greentumble.com/environmental-impacts-of-fuel-dumping/