This is actually lower than when I'd like them to be married.
For me, an ideal system would be to marry off boys and girls at the age of about 16-18,. Boys wouldn't have to be virgins but girls would have to be. You'd have a permanent class of easily available prostitutes for boys to "sow their wild oats" before they can marry at the mentioned age of 16-18. It's how Athenian Republic, the most successful society in history (taking technology into account, of course) worked, though I'm not quite sure of the ages, they might have been slightly lower or higher.