user: Question: Name the number of womens singles for 1999 Rio de Janeiro
Columns: ['Year Location', 'Mens Singles', 'Womens Singles', 'Mens Doubles', 'Womens Doubles']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['2012 Santos', 'Oh Sang-Eun', 'Kim Kyung-Ah', 'Oh Sang-Eun Ryu Seung-Min', 'Li Jiawei Wang Yuegu']
SQL:

assistant: SELECT COUNT("Womens Singles") FROM "Table" WHERE "Year Location" = '1999 Rio de Janeiro';