-- Database schema
| festival_detail : Festival_ID [ INT ] primary_key , Festival_Name [ TEXT ] , Chair_Name [ TEXT ] , Location [ TEXT ] , Year [ INT ] , Num_of_Audience [ INT ] | artwork : Artwork_ID [ INT ] primary_key , Type [ TEXT ] , Name [ TEXT ] | nomination : Artwork_ID [ INT ] primary_key nomination.Artwork_ID = artwork.Artwork_ID , Festival_ID [ INT ] nomination.Festival_ID = festival_detail.Festival_ID , Result [ TEXT ] |
-- -- 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';