Complex sentence: During this era, only Atlético offered Real any serious challenge, winning La Liga titles in 1966,1970,1973 and 1977 and finishing runners-up in 1961,1963 and 1965.
Split into simpler sentences: During this era only Atlético offered Real any serious challenge, winning La Liga titles in 1966,1970,1973 and 1977. They were also runners-up in 1961,1963 and 1965.