user: Question: Which source shows Blackberry at 2.9%?
Columns: ['Source', 'Date', 'Method', 'iOS', 'Android', 'BlackBerry', 'Symbian / Series 40', 'Bada', 'Windows', 'Other']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['comScore Reports (US only)', 'May-13', 'subscribers, US', '39.20%', '52.40%', '4.80%', '0.40%', 'N/A', '3.00%', 'N/A']
SQL:

assistant: SELECT "Source" FROM "Table" WHERE "BlackBerry" = '2.9%';