user: Question: What's the highest grid of ronnie bremer, who had more than 18 points?
Columns: ['Driver', 'Team', 'Laps', 'Time/Retired', 'Grid', 'Points']
Types: ['text', 'text', 'real', 'text', 'real', 'real']
Sample row: ['Sébastien Bourdais', 'Newman/Haas Racing', 81.0, '1:46:29.768', 4.0, 34.0]
SQL:

assistant: SELECT MAX("Grid") FROM "Table" WHERE "Driver" = 'ronnie bremer' AND "Points" > 18.0;