The majority of transactions are transaction spam. But is that really what you're asking for when talking about "the Bitcoin economy"? Even if you'd find actual transaction volume, which is
not the Bitcoindays destroyed (though those are a good measure), it doesn't tell you which sector is most important for Bitcoin to succeed as a currency. For that, you'd need profit margins compared to a situation where Bitcoins don't exist.
If you're asking what determines price, I'd estimate that the vast majority is speculative hoarding, then there's Silk Road drug dealing, and online gambling like Poker, Satoshidice, w/e. There may be people using Bitcoin for repeated international transactions, it would be invisible to us. But I'm not so sure the people who need that most have properly crossed the digital divide yet.
Either way, the question is: what is the question?
(You know the answer is 42.
)