Sale 1:

Sold for 22 keys

Seller: https://backpack.tf/profiles/76561198873310521#!/compare/1548460800/1548547200

Buyer: https://backpack.tf/profiles/76561198312571585#!/compare/1548460800/1548547200

https://backpack.tf/item/4818244804

X = 22

Sale 2:

Sold for 19 keys

Seller: https://backpack.tf/profiles/76561198337734785#!/compare/1550361600/1550448000

Buyer: https://backpack.tf/profiles/76561198089298088#!/compare/1550361600/1550448000

https://backpack.tf/item/5916887121

X = 19

Sale 3:

Quicksold for 17 keys

Seller: https://backpack.tf/profiles/76561198002757046#!/compare/1548288000/1548374400

Buyer: https://backpack.tf/profiles/76561198873310521#!/compare/1548288000/1548374400

https://backpack.tf/item/4818244804

X = 17

Sale 4:

Sold to a quickbuyer for 16 keys

Seller: https://backpack.tf/profiles/76561198119563409#!/compare/1548288000/1548374400

Buyer: https://backpack.tf/profiles/76561198002757046#!/compare/1548288000/1548374400

https://backpack.tf/item/4818244804

X = 16

Other Sales:

https://backpack.tf/item/5916887121 (#1 & #2)

https://backpack.tf/item/4818244804 (#3-

#1

Untraceable

https://backpack.tf/profiles/76561198080212152#!/compare/1549065600/1549152000

https://backpack.tf/profiles/76561198337734785#!/compare/1549065600/1549152000

#2

Untraceable

https://backpack.tf/profiles/76561198089298088#!/compare/1550534400/1550707200

https://backpack.tf/profiles/76561198097840214#!/compare/1550016000/1552089600

#3

Bulk for Scorching Gauzed Gaze

https://backpack.tf/profiles/76561198062779400#!/compare/1548115200/1548201600

https://backpack.tf/profiles/76561198119563409#!/compare/1548115200/1548288000

#4

Sold for Cauldron Bubbles Rubber Glove

https://backpack.tf/profiles/76561198312571585#!/compare/1548547200/1548633600

https://backpack.tf/profiles/76561198165055074#!/compare/1548547200/1548633600

#5

Sold for Cloud 9 Furious Fukaa + Stormy Ol’ Snaggletooth (11) + Pocket Villians

Seller: https://backpack.tf/profiles/76561198165055074#!/compare/1548633600/1548720000

Buyer: https://backpack.tf/profiles/76561198208582767#!/compare/1548547200/1548720000

Given buyers at ~13.5 keys on the Fukaa, this sale is gonna be significantly higher than the unsold at 24 keys. Excluding this sale.

#6

Untraceable

https://backpack.tf/profiles/76561198179607307#!/compare/1549065600/1549497600

https://backpack.tf/profiles/76561198072898758#!/compare/1549497600/1549584000

#7

Untraceable

https://backpack.tf/profiles/76561198072898758#!/compare/1549497600/1549584000

https://backpack.tf/profiles/76561198064065041#!/compare/1549065600/1549497600

#8

Untraceable

https://backpack.tf/profiles/76561198064065041#!/compare/1549065600/1549497600

https://backpack.tf/profiles/76561198156570751#!/compare/1549411200/1549497600

#9

Bulk for Green Energy Rack

https://backpack.tf/profiles/76561198156570751#!/compare/1549584000/1549670400

https://backpack.tf/profiles/76561198232041512#!/compare/1549584000/1549670400

Sellers:

Sales at:

16

17

19

22

https://i.imgur.com/WKgrol7.png - Buyers at 16+, excluding 16.

17 quicksold, excluding 17.

Going with 19-22.