In the first week of July, a record 1,100 people went to the local swimming pool. In the second week, 100 fewer people went to the pool than in the first week. In the third week, 130 more people went to the pool than in the second week. In the fourth week, 350 fewer people went to the pool than in the third week. What is the percent decrease in the number of people who went to the pool over these four weeks?