CREATE TABLE festival_detail (festival_id NUMBER, festival_name CLOB, chair_name CLOB, location CLOB, year NUMBER, num_of_audience NUMBER)
CREATE TABLE nomination (artwork_id NUMBER, festival_id NUMBER, result CLOB)
CREATE TABLE artwork (artwork_id NUMBER, type CLOB, name CLOB)

In which year are there festivals both inside the 'United States' and outside the 'United States'?
SELECT year FROM festival_detail WHERE location = 'United States' INTERSECT SELECT year FROM festival_detail WHERE location <> 'United States'
SELECT "year" FROM "festival_detail" WHERE "location" = 'United States' INTERSECT SELECT "year" FROM "festival_detail" WHERE "location" <> 'United States'