user: Question: What is the lowest rank of Gatwick Airport? 
Columns: ['Rank', 'Railway Station', 'Annual entry/exit (millions) 2011–12', 'Annual interchanges (millions) 2011–12', 'Total Passengers (millions) 2011–12', 'Location', 'Main Services', 'Number of Platforms']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'London Waterloo', '94.046', '9.489', '103.534', 'London', 'South Western Main Line West of England Main Line', 19.0]
SQL:

assistant: SELECT MIN("Rank") FROM "Table" WHERE "Railway Station" = 'Gatwick Airport';