user: Question: What is the smallest fleet size with a type of Shunter introduced in 1953?
Columns: ['Class', 'Type', 'Introduced', 'Fleet Size', 'Numbers']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Class 08', 'Shunter', '1953', 2.0, '08925, 08934']
SQL:

assistant: SELECT MIN("Fleet Size") FROM "Table" WHERE "Type" = 'Shunter' AND "Introduced" = '1953';