[fsloth]

"I would rather see $ spent per person"

If the research is constrained by resources that can be acquired from global markets, then, yeah.

However, a lot of research tends to consume capital in form of wages to researchers. In this instance a percentage of GDP is a much better indicator of the resourcing level of research.

However, I don't know if there is any way to compare research on a high level by any financial meter in a way that would not be open to critique.