Complex sentence: In 2015, the format changed from 17 regional events (one for each region) to 8: each "super-regional" event includes qualifiers from two or three regions, totalling 40 or 50 athletes.
Split into simpler sentences: In 2015, the format changed from 17 regional events (one for each region) to eight. Each "super-regional" event includes qualifiers from two or three regions, totaling 40 or 50 athletes.