I have to agree that older is better... I fit right in with those statistics.
My first marriage was when I was less than 21, and that was a complete disaster, ending in divorce. The Mister and I got married between the ages of 23-24, and it has been *very* difficult to make our marriage work. We have succeeded, but I can tell you right now that if I could do it all over again, I would have waited until I was closer to 30 and really understood what being married meant before I made such a big commitment.
That said, there are always exceptions to the rule! I am sure many people get married young and have no problem with it, but I think the majority of people hardly understand themselves let alone know how to relate to another when they are under 30.