user: ### NOW ANSWER:
Question: What is the Frequency MHz for the station with a call sign of W224BN?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['W266AH', 101.1, 'Athens, Georgia', 10.0, 'D', 'FCC']
SQL:

assistant: SELECT AVG("Frequency MHz") FROM "Table" WHERE "Call sign" = 'W224BN';