user: Question: What is the average ERP W when the call sign is WHRE?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['WHRE', 91.9, 'Eastville, Virginia', 4400.0, 'A', 'FCC']
SQL:

assistant: SELECT AVG("ERP W") FROM "Table" WHERE "Call sign" = 'WHRE';