user: Question: Name the average pop for Chūgoku and prefecture of Okayama
Columns: ['Capital', 'Prefecture', 'Region', 'Island', 'Pop. ¹']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Akita', 'Akita', 'Tōhoku', 'Honshū', 327651.0]
SQL:

assistant: SELECT AVG("Pop. ¹") FROM "Table" WHERE "Region" = 'Chūgoku' AND "Prefecture" = 'Okayama';