The number of entrants has increased greatly in recent years. In the 2004–05 season, 660 clubs entered the competition, beating the long-standing record of 656 from the 1921–22 season. In 2005–06 this increased to 674 entrants, in 2006–07 to 687, in 2007–08 to 731 clubs, and for the 2008–09 and 2009–10 competitions it reached 762. The number has varied slightly but remained roughly stable since then, with 759 clubs participating in 2010–11, a record 763 in 2011–12, 758 for 2012–13, 737 for 2013–14 and 736 for 2014–15. By comparison, the other major English domestic cup, the League Cup, involves only the 92 members of the Premier League and Football League.

Answer this question, if possible (if impossible, reply "unanswerable"): How many clubs entered in 2006-07?
687