Three of the four new shows of the 2015-2016 Broadway season have excelled at the summer box office, dispelling the myth that premiering during the summer is a ticket to dwindling audiences and financial strife. According to research by the Broadway League, the hip-hop musical “Hamilton” and the plays “Penn & Teller on Broadway” and “An Act of God” have had a strapping showing at the box office, grossing over $1 million a week by the end of July. Conversely, the fourth show of the new season, the musical “Amazing Grace,” continues to struggle as the lowest grossing performance currently on Broadway.