user: Question: What is the average decile of Ruapehu College, which has a State authority?
Columns: ['Name', 'Years', 'Area', 'Authority', 'Decile', 'Roll']
Types: ['text', 'text', 'text', 'text', 'real', 'real']
Sample row: ['Kaitieke School', '1–8', 'Kaitieke', 'State', 8.0, 11.0]
SQL:

assistant: SELECT AVG("Decile") FROM "Table" WHERE "Authority" = 'State' AND "Name" = 'Ruapehu College';