Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_30 (year VARCHAR, venue VARCHAR, opposition VARCHAR)
### Question:
Which number of Years has a Venue of old trafford, and an Opposition of yorkshire?
### Answer:
SELECT COUNT(year) FROM table_name_30 WHERE venue = "old trafford" AND opposition = "yorkshire"