user: Question: What year was the carriage type is 47' 6" 'Birdcage' gallery coach built
Columns: ['Number', 'TMS Number', 'Builder', 'Year built', 'Carriage type']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['A 595', 'A 50702', 'NZR Addington', 1900.0, '47\' 6" \'Birdcage\' gallery coach']
SQL:

assistant: SELECT "Year built" FROM "Table" WHERE "Carriage type" = '47'' 6" ''Birdcage'' gallery coach';