See, now you screwed up. They have not "done better". They've lived a lower quality of life. They've suffered greater oppression, and less freedom. They're below us in nearly every imaginable metric. This is different than improving beyond where we were. It's harder to improve when you're already so high.
If you want to look to a country as a beacon to the rest of the world for that date range, in terms doing the best job to improve the quality of their citizen's lives, the country to study is Oman. And what did they do? They secured sprawling contracts with the US government and US companies, and other western capitalist countries. They signed deals that committed foreign companies to teach their workers skills. They reinvested enormous amounts into their infrastructure (not welfare state policies). And they sure as hell didn't flood their country with impoverished Yemeni "migrants" seeking asylum.