Complex sentence: Henri Langlois, Georges Franju, and Jean Mitry, founded the "Cinémathèque Française" (a Paris-based film theater and museum) in 1936 which progressed from ten films in 1936 to more than 60,000 films by the early 70s.
Split into simpler sentences: Henri Langlois, Georges Franju, and Jean Mitry founded the "Cinémathèque Française" (a Paris-based film theater and museum) in 1936. It grew from ten films in 1936 to more than 60,000 films by the early 70s.