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_31 (year INTEGER, extra VARCHAR)
### Question:
Tell me the sum of year for extra of junior team competition
### Answer:
SELECT SUM(year) FROM table_name_31 WHERE extra = "junior team competition"