A Work in progress...
In 1900 - Anglo-American rapprochement and informal alliance.
In 1950 - NATO, ECSC
In 1975 - NATO expansion, EC expanded and deepened, OECD, IEA, NAA, G-6
In 2000 - NATO further expanded and transformed, EU, OECD, IEA, G-8, NPA, EAPC, PfP, NRC
In 2025 ...The history of the next level of institutionalization is still being written
From The Democracy Advantage: How Democracies Promote Prosperity and Peace, Routledge, p. 11