Passage: Trabelsi made his international debut in May 1998, shortly before the 1998 World Cup. He also played in all of Tunisia's matches in the 2002 FIFA World Cup and 2006 FIFA World Cups, as well as the 2004 African Nations Cup, which Tunisia won. Following Tunisia's elimination from the 2006 World Cup after a 1–0 defeat to Ukraine, Trabelsi announced his retirement from international football at the age of 29, with 61 caps and one goal. He scored his only goal for the national team in 2006 in a friendly match against Ghana.

Question: How old was Trabelsi when he retired in 2006?
29