user: Question: What is the average episode that has September 11, 2007 as a region 1?
Columns: ['Volume', 'Discs', 'Episodes', 'Region 1 release', 'Region 2 release', 'Region 4 release']
Types: ['text', 'real', 'real', 'text', 'text', 'text']
Sample row: ['1', 1.0, 5.0, 'January 23, 2007', 'Not released', 'June 4, 2009']
SQL:

assistant: SELECT AVG("Episodes") FROM "Table" WHERE "Region 1 release" = 'September 11, 2007';