user: Question: When did series 6 start?
Columns: ['Series', 'Start date', 'End date', 'Episodes', 'Average viewers (millions)']
Types: ['real', 'text', 'text', 'real', 'text']
Sample row: [1.0, '22 August 2009', '3 October 2009', 7.0, '5.09']
SQL:

assistant: SELECT "Start date" FROM "Table" WHERE "Series" = 6.0;