Complex sentence: The seating capacity was 15,000 from 1971 until 1977, raised to 32,000 in 1978, and to 36,800 in 1999.
Split into simpler sentences: The seating capacity was 15,000 from 1971 until 1977. The capacity was raised to 32,000 in 1978, and then to 36,800 in 1999.