Many professional sports teams increase their ticket prices every year but they keep selling out their home games. What could be the reason for fans who buy the tickets for buying the same number of tickets as prices rise. Is this because of a change in demand (increase or decrease), change in supply (increase or decrease) , a change in both demand and supply (increase or decrease), or just a violation of the law of demand? Please give an explanation.

You may assume that the size of the stadium and the number of different categories of seats does not change.

(Law of demand states that price and quantity demanded are inversely related. When price rises quantity demanded falls and when price falls quantity demanded rises).