There has been a rapid increase in the number of chances to wear casual clothes since I entered the university.
The number of opportunities to wear casual clothes has increased rapidly since I entered the university.
大学に入ってから私服を着る機会が急激に増えた
大学に入ってから since I entered the university
私服を着る wear casual clothes
機会 chance, opportunity
急激な rapid （形容詞）急激に rapidly （副詞）
増える increase （動詞、名詞）
There has been a rapid increase in the number of chances to wear casual clothes since I entered the university.
大学に入ってから私服を着る回数が急激に増えた
The number of opportunities to wear casual clothes has increased rapidly since I entered the university.
大学に入ってから私服を着る機会が急激に増えた
日本 
