It's been interesting tracking powder stock as it appears and disappears. You can see pretty substantial spikes where popular powders appear and disappear rapidly, and the slower downward curves for the less popular stuff. That's not at all surprising, but it's an interesting view of what powders are really niche or just not used much at all. Following those you tend to see a gentle slope and then it drops, which tells me a lot of desperate people see the table scraps of these unpopular powders and think "well, I guess I can find a way to use this?"