3 ms·

That is well studied. A large meta-analysis claims 2.93 points per decade, over most of the 20th century. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4152423/

by tlb 9y ago

That is well studied. A large meta-analysis claims 2.93 points per decade, over most of the 20th century. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4152423/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4152423/