user: Question: How many mixed doubles were there in the year that Olga Koseli won the women's singles?
Columns: ['Year', 'Mens singles', 'Womens singles', 'Mens doubles', 'Womens doubles', 'Mixed doubles']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1995.0, 'Vitalii Sekerinau', 'Olga Koseli', 'Maxim Karpenko Vitalii Sekerianu', 'Marina Buruian Tatiana Gazia', 'Maxim Karpenko Marina Buruian']
SQL:

assistant: SELECT COUNT("Mixed doubles") FROM "Table" WHERE "Womens singles" = 'Olga Koseli';