Read this: Current manager, Roberto Martínez, is the fourteenth permanent holder of the position since it was established in 1939. There have also been four caretaker managers, and before 1939 the team was selected by either the club secretary or by committee. The club's longest-serving manager has been Harry Catterick, who was in charge of the team from 1961–73, taking in 594 first team matches. The Everton manager to win most domestic and international trophies is Howard Kendall, who won two Division One championships, the 1984 FA Cup, the 1984 UEFA Cup Winners' Cup, and three Charity Shields.

In what year did Roberto Martinez become the current manager of Everton?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable