user: Question: On July 17, 2008, what was the total number of lead maragin? 
Columns: ['Poll Source', 'Dates administered', 'Democrat: Mark Begich', 'Republican: Ted Stevens', 'Lead Maragin']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Rasmussen Reports', 'October 28, 2008', '52%', '44%', 8.0]
SQL:

assistant: SELECT SUM("Lead Maragin") FROM "Table" WHERE "Dates administered" = 'July 17, 2008';