I want to know the answer to the following question:
Including Arsenal, how many  teams  had won the Premier League up to 2013?
All the background I'm provided with is that "As of July 2013, they were one of only five teams, the others being Manchester United, Blackburn Rovers, Chelsea, and Manchester City, to have won the Premier League since its formation in 1992.". Is that enough to answer the question?
Answer: yes