There's a lot more histories you gotta look at unfortunately.

Active Histories

https://backpack.tf/item/12126607345

https://backpack.tf/item/12026612641

https://backpack.tf/item/11958658507

https://backpack.tf/item/11943224361

https://backpack.tf/item/11939822836

https://backpack.tf/item/11924257061

https://backpack.tf/item/11920889765

https://backpack.tf/item/11919877382

2 Sales on mp.tf (https://marketplace.tf/items/tf2/31262;5;u60)

1 @ 24.99 - 24.99 / 1.98 ~ 12 keys

1 @ 24.99 - 24.99 / 1.97 ~ 12 keys

4 sales on mannco.store (https://mannco.store/item/440-dead-presidents-unusual-undercover-brolly)

1 @ 21.99 - 21.99 / 1.77 ~ 12 keys

1 @ 18.94 - 18.94 / 1.86 ~ 10 keys

1 @ 18.95 - 18.95 / 1.83 ~ 10 keys

1 @ 19.98 - 19.98 / 1.88 ~ 10 keys

I feel like I range of 9-12 would work better here. But I only accounted for the mp.tf and mannco sales. Maybe you could look through the rest?