user: Question: What is the highest cable ranking?
Columns: ['Episode no.', 'Airdate', 'Viewers', 'BBC Three weekly ranking', 'Cable rank']
Types: ['real', 'text', 'real', 'real', 'real']
Sample row: [1.0, '24 March 2011', 783000.0, 8.0, 17.0]
SQL:

assistant: SELECT MAX("Cable rank") FROM "Table";