user: Question: How many hosts were on Seven Network?
Columns: ['Country', 'Local Name', 'Host', 'Channel', 'Year Aired', 'Top Prize']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Australia', 'The Rich List', "Andrew O'Keefe", 'Seven Network', '2007-2009', '$250,000']
SQL:

assistant: SELECT COUNT("Host") FROM "Table" WHERE "Channel" = 'Seven Network';