CREATE TABLE record (id DECIMAL, result TEXT, swimmer_id DECIMAL, event_id DECIMAL)
CREATE TABLE swimmer (id DECIMAL, name TEXT, nationality TEXT, meter_100 DECIMAL, meter_200 TEXT, meter_300 TEXT, meter_400 TEXT, meter_500 TEXT, meter_600 TEXT, meter_700 TEXT, time TEXT)
CREATE TABLE event (id DECIMAL, name TEXT, stadium_id DECIMAL, year TEXT)
CREATE TABLE stadium (id DECIMAL, name TEXT, capacity DECIMAL, city TEXT, country TEXT, opening_year DECIMAL)

What is the average capacity of the stadiums that were opened in year 2005?
SELECT AVG(capacity) FROM stadium WHERE opening_year = 2005
SELECT AVG("capacity") FROM "stadium" WHERE "opening_year" = 2005