And, if it's not that, it's all of the new corporate mines that have popped up.  Generally, IMO, they're not interested in Bitcoin other than to load up on fiat, and since these operations are huge they're taking most of the newly mined coins and dumping them on the market for fiat.  In years past, the mining base was much more spread out and mining participants, on average, were more intereseted in building BTC reserves than the fiat equivalent.  This concept coupled with the fact that at low prices the daily volume was much greater meant that any new coins mined that did make it to market had little effect on the exchange rate.  Now, with higher price, lower volume, and corporate mines with no interest in holding BTC you get an ever increasing supply of fresh coins comparative to historical time frames.