user: Question: What is the highest numbered nightly rank for any episode? 
Columns: ['Order', 'Episode', 'Original airdate', 'Timeslot', 'Viewers (100000s)', 'Nightly rank', 'Weekly rank']
Types: ['real', 'text', 'text', 'text', 'text', 'real', 'real']
Sample row: [1.0, '"818-Jklpuzo"', 'September 28, 2009', 'Monday 8:00 pm – 8:30 pm', '13.27', 6.0, 16.0]
SQL:

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