Complex sentence: By 1976, when "Midway" opened, there were over 800 Sensurround equipped theaters in the USA alone-worldwide, there were over 2000 Sensurround theaters.
Split into simpler sentences: By 1976, when "Midway" opened, there were over 800 Sensurround equipped theaters in the USA alone. Worldwide, there were over 2000 Sensurround theaters.