Are Buddhists happier people?

The First Noble Truth says that cyclic existence is Dukkha. I'm not in a position to expound on the meaning of the word Dukkha, but I think everyone can agree it does not mean "happines". Still, I think many Buddhists would say they are more happy in their lives than non Buddhists. Would it be fair to claim that Buddhists, if they practice well, can expect to be more content and generally more happy in their lives? And if so, is this because of Buddhism or is it more generally because they have a spiritual outlook on life?