Complex sentence: Only two horses contested the race in 1918,1920,1944, and 1946; however, due to the large number of entries in 1976 and 1985 it was run in two divisions.
Split into simpler sentences: Only two horses contested the race in the years 1918,1920,1944, and 1946. Due to the large number of entrants in 1976 and 1985 it was run in two divisions.