Among the restaurants located on the street number ranges from 1000 to 2000, what is the percentage of Afghani restaurants are there?
street number ranges from 1000 to 2000 refers to 1000 < = street_num < = 2000; Afghani restaurant refers to food_type = 'afghani'; percentage = divide(count(id_restaurant where food_type = 'afghani'), count(id_restaurant)) * 100%
SELECT CAST(SUM(IIF(T2.food_type = 'afghani', 1, 0)) AS REAL) * 100 / COUNT(T1.id_restaurant) FROM location AS T1 INNER JOIN generalinfo AS T2 ON T1.id_restaurant = T2.id_restaurant WHERE 1000 <= T1.street_num <= 2000