The filamentous actinomycetes make around two thirds of all known natural product antibiotics and about half of the clinically used antibiotics.
Most of these were discovered during the Golden Age which ran from the 1940s to the 1960s.
Figures are taken from: Hutchings MI, Truman A and Wilkinson B (2019). Antibiotics: past, present and future. Curr. Op. Microbiol. Under review.