Complex sentence: O'Donnell left in 1980, Woolery in 1981, and Stafford in 1982; they were replaced, respectively, by Jack Clark, Pat Sajak, and Vanna White.
Split into simpler sentences: O'Donnell left in 1980, Woolery in 1981, and Stafford in 1982. They were replaced, respectively, by Jack Clark, Pat Sajak, and Vanna White.