What is usos 2015?

As an AI language model, my training data only goes up to mid-2021. However, here is some general information about US Open Series (USOS) in 2015:

The US Open Series is a summer tennis tour leading up to the US Open, with multiple tournaments played across North America. In 2015, the USOS began on July 20 and concluded on August 30. The series consisted of ten tournaments:

1. BB&T Atlanta Open: July 20 - July 26
2. Citi Open: July 27 - August 2
3. Rogers Cup (men's): August 10 - August 16
4. Rogers Cup (women's): August 10 - August 16
5. Western & Southern Open: August 16 - August 23
6. Winston-Salem Open: August 23 - August 29
7. Connecticut Open: August 24 - August 29
8. WTA New Haven Open: August 21 - August 29
9. ATP New Haven Open: August 23 - August 29
10. US Open: August 31 - September 13

Players earned points at each tournament based on their performance, and at the end of the series, the top three men and top three women with the most points earned a bonus prize of $1 million. In 2015, the winners of the USOS were Serena Williams, Novak Djokovic, Dominika Cibulkova, John Isner, Simona Halep, and Andy Murray.