user: Question: What was the weight in kg when the jockey was B. York? 
Columns: ['Result', 'Date', 'Race', 'Venue', 'Group', 'Distance', 'Weight (kg)', 'Jockey', 'Winner/2nd']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['2nd', '02 Aug 1996', '3yo Hcp Restricted', 'Rosehill', 'NA', '1500 m', '55', 'J. Marshall', '1st - Spy Cracker']
SQL:

assistant: SELECT "Weight (kg)" FROM "Table" WHERE "Jockey" = 'B. York';