The best we can say for that chart is that there is some relation (not necessarily casual) between GDP and mathematical education levels.
The causal factor could be anything - but it's a damn pretty curve. It at least suggests that measuring a country's gdp can give you a ballpark figure for it's mathematical education levels.
Might be a novel premise for funding to explore if math is a causal factor.
The best we can say for that chart is that there is some relation (not necessarily casual) between GDP and mathematical education levels.
The causal factor could be anything - but it's a damn pretty curve. It at least suggests that measuring a country's gdp can give you a ballpark figure for it's mathematical education levels.
Might be a novel premise for funding to explore if math is a causal factor.
Could also be education - rising tide lifts all boats thing - rather than mathematics specifically.