The short-term data pretty much confirms what I've been seeing. It hovers just around 300 during lock-box events. In between them, however, I sometimes see it go as low as 220, but mostly sticking to around 250.
You may want to consider tightening up your graph a bit. Last time I took a stats course, and I;ll admit that it;s been a couple of decades, my understanding is that the high and low points of a graph should fall within the 50-70% range of the plus and minus of the y axis. If possible.