Sale 1:

untrace/bulk

https://backpack.tf/profiles/76561198079515445#!/compare/1538870400/1538956800

https://backpack.tf/profiles/76561198197481041#!/compare/1538956800/1539129600

Sale 2:

untrace

https://backpack.tf/profiles/76561198197481041#!/compare/1541030400/1541116800

https://backpack.tf/profiles/76561198053252981#!/compare/1541203200/1541289600

Sale 3:

untrace

https://backpack.tf/profiles/76561198390040170#!/compare/1542758400/1542844800

https://backpack.tf/profiles/76561198355617277#!/compare/1541721600/1543622400

Sale 4:

untrace

https://backpack.tf/profiles/76561198355617277#!/compare/1543795200/1544140800

https://backpack.tf/profiles/76561198819564432#!/compare/1543708800/1543795200

Sale 5:

untrace

https://backpack.tf/profiles/76561198819564432#!/compare/1543795200/1543881600

https://backpack.tf/profiles/76561198386673294#!/compare/1543795200/1543881600

Sale 6:

Maybe something missing/seems low

Sold for Strange Pro KS Bloom Buffed Tomislav

https://backpack.tf/profiles/76561198386673294#!/compare/1543881600/1544054400

https://backpack.tf/profiles/76561198047819527#!/compare/1543968000/1544054400

Sale 7:

Bulk/using there

https://backpack.tf/profiles/76561198024867201#!/compare/1544659200/1544745600

https://backpack.tf/profiles/76561198047819527#!/compare/1544400000/1544745600

Sale 8:

untrace

https://backpack.tf/profiles/76561198024867201#!/compare/1545609600/1545696000

https://backpack.tf/profiles/76561197995376241#!/compare/1545177600/1545696000

Sale 9-12:

https://marketplace.tf/items/185;5;u32

$16.99 / $1.77 = 9.60 keys

$14.4 / $1.76 = 8.18 keys [ Excluding as 29 cents away from buy orders: https://imgur.com/a/5ELdmTJ ]

$14.4 / $1.72 = 8.37 keys [ Excluding as 29 cents away from buy orders: https://imgur.com/a/5ELdmTJ ]

$15.99 / $1.73 = 9.24 keys

Sales 9.24 and 9.6

Rounding to 9-9.5