Table schema:
CREATE TABLE accelerator_compatible_browser (compatible_since_year VARCHAR, browser_id VARCHAR, accelerator_id VARCHAR); CREATE TABLE browser (id VARCHAR, name VARCHAR); CREATE TABLE web_client_accelerator (id VARCHAR, name VARCHAR)

Question: When did the web accelerator 'CACHEbox' and browser 'Internet Explorer' become compatible?
SQL: SELECT T1.compatible_since_year FROM accelerator_compatible_browser AS T1 JOIN browser AS T2 ON T1.browser_id = T2.id JOIN web_client_accelerator AS T3 ON T1.accelerator_id = T3.id WHERE T3.name = 'CACHEbox' AND T2.name = 'Internet Explorer'