user: Question: How many were hosted whene the average attendance was 27638?
Columns: ['Team', 'Hosted', 'Average', 'Highest', 'Lowest', 'Total', 'Last Year', 'Up/Down']
Types: ['text', 'real', 'real', 'real', 'real', 'real', 'real', 'text']
Sample row: ['Essendon', 11.0, 51790.0, 83905.0, 29528.0, 569685.0, 48353.0, '+ 3437']
SQL:

assistant: SELECT "Hosted" FROM "Table" WHERE "Average" = 27638.0;