Database schema:

CREATE TABLE generalinfo (
	id_restaurant INTEGER NOT NULL -- example: ['2', '1'],
	label TEXT -- example: ['kabul afghan cuisine', "sparky's diner"],
	food_type TEXT -- example: ['afghani', '24 hour diner'],
	city TEXT -- example: ['san francisco', 'san carlos'],
	review REAL -- example: ['2.3', '3.8'],
	PRIMARY KEY (id_restaurant), 
	CONSTRAINT fk_generalinfo_geographic FOREIGN KEY(city) REFERENCES geographic (city)
)


CREATE TABLE geographic (
	city TEXT NOT NULL -- example: ['alamo', 'alameda'],
	county TEXT -- example: ['alameda county', 'contra costa county'],
	region TEXT -- example: ['napa valley', 'bay area'],
	PRIMARY KEY (city)
)


CREATE TABLE location (
	id_restaurant INTEGER NOT NULL -- example: ['2', '1'],
	street_num INTEGER -- example: ['242', '135'],
	street_name TEXT -- example: ['church st', 'el camino real'],
	city TEXT -- example: ['san francisco', 'san carlos'],
	PRIMARY KEY (id_restaurant), 
	CONSTRAINT fk_location_geographic FOREIGN KEY(city) REFERENCES geographic (city),
	CONSTRAINT fk_location_generalinfo FOREIGN KEY(id_restaurant) REFERENCES generalinfo (id_restaurant)
)

Question: What percentage of restaurants are from the Bay Area?
Evidence: Bay Area refers to region = 'bay area'; percentage = divide(count(id_restaurant where region = 'bay area'), count(id_restaurant)) * 100%

SQL:
SELECT CAST(SUM(IIF(T1.region = 'bay area', 1, 0)) AS REAL) * 100 / COUNT(T2.id_restaurant) FROM geographic AS T1 INNER JOIN location AS T2 ON T1.city = T2.city