Resuggesting, thank you Mindacos! However, there should be consistency with the rounding measures.

3 years outdated.

Sold for 10 keys

https://backpack.tf/profiles/76561198341171690#!/compare/1588550400/1588636800

https://backpack.tf/profiles/76561198080869146#!/compare/1584748800/1591488000

ID's match.

Sold for Blizzardy Bicorne (12.5 keys)

https://backpack.tf/profiles/76561198299954141#!/compare/1590796800/1590969600

https://backpack.tf/profiles/76561198363653975#!/compare/1590624000/1590969600

Some round to 12, others round to 13, ill round to 13 here.

Untrace

https://backpack.tf/profiles/76561198355796365#!/compare/1591747200/1591833600

https://backpack.tf/profiles/76561198100484031#!/compare/1591747200/1591833600

Sold for 9 keys

https://backpack.tf/profiles/76561198157274202#!/compare/1591660800/1591747200

https://backpack.tf/profiles/76561198355796365#!/compare/1591660800/1591747200

Untrace

https://backpack.tf/profiles/76561198410048192#!/compare/1590710400/1590796800

https://backpack.tf/profiles/76561198895128280#!/compare/1590624000/1590710400

Untrace

https://backpack.tf/profiles/76561198895128280#!/compare/1590710400/1590796800

https://backpack.tf/profiles/76561198081962061#!/compare/1590710400/1590796800

Untrace

https://backpack.tf/profiles/76561198081962061#!/compare/1590883200/1590969600

https://backpack.tf/profiles/76561198419584303#!/compare/1590796800/1590883200

Untrace

https://backpack.tf/profiles/76561198363653975#!/compare/1591142400/1591228800

https://backpack.tf/profiles/76561198106795971#!/compare/1582156800/1591142400

Sold for 19.99 on April 15, 2020

19.99/1.77 = 11.29 rounding to 11 keys

https://marketplace.tf/items/tf2/384;5;u56

Classifieds:

https://gyazo.com/d22dfc9edb793d8eaa161cf1168f0c2b

1 @ 9 keys

1 @ 10 keys

1 @ 11 keys

1 @ 13 keys

Taking a range of 9-13 keys here.