Warp, I wish I knew for sure which of us has the "good" data. {NG} In any event, your point about the spike low on my chart is well taken.
BTW, due to my difficulties with one of the more "interesting" idiosyncracies of Excel, I'm not sure if the data on that previous chart is any good. So, I redid everything and came up with the following charts.
The first two charts are the "raw" net percentage up & down volume, respectively. Not very useful, methinks, unless one were to keep the chart down to say six months or less. The second pair of charts display 5 and 13 day SMAs of up and down volume, respectively. They may be more useful.