Complex sentence: STAR was found in 1977 and currently has 5,500 members, which represents over 40% of all business administration students in the Netherlands, making it the largest student-led organization in Europe.
Split into simpler sentences: STAR was found in 1977 and currently has 5,500 members, which represents more than 40% of all business administration students in the Netherlands. STAR is the largest student-led organization in Europe.