That maths don't add up. If 200 countries need to do 989bn, then they need to do 4.945, let's say 5. If we consider countries with more population are going to

That maths don't add up. If 200 countries need to do 989bn, then they need to do 4.945, let's say 5. If we consider countries with more population are going to plant more (so trees per capita perhaps). We could go with landmass but it takes money/people to do this, so let's go with capita. Pakistan being a highly populated country and so needs to plan more than the 5bn average (they did 10). But there is a very long tail of small countries in that list of 200 so many more small countries. Most will go below the average needed and so won't stack up.