Just assuming a normal curve - regardless of the threshold of "minimum ability to count as a researcher" one would expect between two comparable populations of

Just assuming a normal curve - regardless of the threshold of "minimum ability to count as a researcher" one would expect between two comparable populations of different sizds more capable of and actively driving research as population grows. Higher GDP is correlated implies higher per person productivity and more specialization to decommoditize themselves vs the global labor. Plus pushing the envelope often requires more funding for novel projects as there isn't an off the shelf for something novel to reduce costs. They aren't perfect measures by any means (there exist things which boost either not research) but are decent enough proxies.