user: Question: Which number of Years has a Venue of old trafford, and an Opposition of yorkshire?
Columns: ['Opposition', 'Score', 'Venue', 'City', 'Year']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Derbyshire', '589', 'Stanley Park', 'Blackpool', 1994.0]
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Venue" = 'old trafford' AND "Opposition" = 'yorkshire';