CREATE TABLE Web_client_accelerator (id INT, name TEXT, Operating_system TEXT, Client TEXT, Connection TEXT)
CREATE TABLE accelerator_compatible_browser (accelerator_id INT, browser_id INT, compatible_since_year INT)
CREATE TABLE browser (id INT, name TEXT, market_share FLOAT)

Find the number of web accelerators used for each Operating system.
SELECT Operating_system, COUNT(*) FROM Web_client_accelerator GROUP BY Operating_system
SELECT "Operating_system", COUNT(*) FROM "Web_client_accelerator" GROUP BY "Operating_system"