user: Question: state the earliest year Li Xuerui won womens singles
Columns: ['Year', 'Mens singles', 'Womens singles', 'Mens doubles', 'Womens doubles', 'Mixed doubles']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [2012.0, 'Chen Long', 'Li Xuerui', 'Mathias Boe Carsten Mogensen', 'Wang Xiaoli Yu Yang', 'Joachim Fischer Nielsen Christinna Pedersen']
SQL:

assistant: SELECT MIN("Year") FROM "Table" WHERE "Womens singles" = 'Li Xuerui';