user: Question: what was Casey Martin's minimum yearly earnings?
Columns: ['Year', 'Tournaments played', 'Cuts made', 'Wins', 'Best finish', 'Earnings ( $ )', 'Money list rank']
Types: ['real', 'real', 'real', 'real', 'text', 'real', 'text']
Sample row: [1998.0, 3.0, 2.0, 0.0, 'T-23', 37221.0, '221']
SQL:

assistant: SELECT MIN("Earnings ( $ )") FROM "Table";