user: Question: How many winning drivers are there when the winning team is Bryan Herta Autosport?
Columns: ['Rd.', 'Race', 'Pole position', 'Fastest lap', 'Most laps led', 'Winning driver', 'Winning team', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', 'St. Petersburg', 'Will Power', 'Hélio Castroneves', 'Dario Franchitti', 'Dario Franchitti', 'Chip Ganassi Racing', 'Report']
SQL:

assistant: SELECT COUNT("Winning driver") FROM "Table" WHERE "Winning team" = 'Bryan Herta Autosport';