### Database Schema:
CREATE TABLE game_publisher (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	game_id	INTEGER	NULL	DEFAULT NULL,
	publisher_id	INTEGER	NULL	DEFAULT NULL,
	foreign key (publisher_id) references publisher (id),
	foreign key (game_id) references game (id)
);

CREATE TABLE game_platform (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	game_publisher_id	INTEGER	NULL	DEFAULT NULL,
	platform_id	INTEGER	NULL	DEFAULT NULL,
	release_year	INTEGER	NULL	DEFAULT NULL,
	foreign key (platform_id) references platform (id),
	foreign key (game_publisher_id) references game_publisher (id)
);

CREATE TABLE platform (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	platform_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE game (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	genre_id	INTEGER	NULL	DEFAULT NULL,
	game_name	TEXT	NULL	DEFAULT NULL,
	foreign key (genre_id) references genre (id)
);

CREATE TABLE genre (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	genre_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE region (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	region_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE region_sales (
	region_id	INTEGER	NULL	DEFAULT NULL,
	game_platform_id	INTEGER	NULL	DEFAULT NULL,
	num_sales	REAL	NULL	DEFAULT NULL,
	foreign key (region_id) references region (id),
	foreign key (game_platform_id) references game_platform (id)
);

CREATE TABLE publisher (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	publisher_name	TEXT	NULL	DEFAULT NULL
);

### User's Query:
Calculate how many percent of sales in North America is higher than the average sale per region for platform ID 9577.

### Extra Knowledge:
in North America refers to region_name = 'North America'; platform ID 9577 refers to game_platform_id = 9577; percent = divide(subtract(num_sales where region_name = 'North America' and game_platform_id = 9577, avg(num_sales)), avg(num_sales)) * 100%
SELECT (SUM(CASE WHEN T2.region_name = 'North America' THEN T1.num_sales ELSE 0 END) - AVG(T1.num_sales)) * 100.0 / AVG(T1.num_sales) FROM region_sales AS T1 INNER JOIN region AS T2 ON T1.region_id = T2.id WHERE T1.game_platform_id = 9577