Agility — one of the subtypes World of Warcraft files under Gem — gets this table as a focused view: the same drill-down the in-game Auction House browser applies when you filter by subcategory.
Agility listings clear and replenish at whatever pace the in-game market sets; some subtypes trade in volume, others sit static for stretches. The price-history chart on each row's detail page makes that pattern visible at a glance.
If you want the full Gem category rather than only Agility, the breadcrumb above steps back up one level; otherwise the table below covers every tracked item in this subclass.