Sale 1:

https://backpack.tf/profiles/76561198180363385#!/compare/1531785600/1531958400

https://backpack.tf/profiles/76561198176088318#!/compare/1528588800/1532649600

Sold for 5 keys

Sale 2:

https://backpack.tf/profiles/76561198242067104#!/compare/1529712000/1529798400

https://backpack.tf/profiles/76561198180363385#!/compare/1529712000/1529884800

Untrace.

Sale 3:

https://backpack.tf/profiles/76561198312583107#!/compare/1530921600/1531008000

https://backpack.tf/profiles/76561198146461519#!/compare/1522454400/1531008000

Untrace.

Sale 4:

https://backpack.tf/profiles/76561198312583107#!/compare/1529452800/1529539200

Untrace.

Sale 5:

https://backpack.tf/profiles/76561198057582763#!/compare/1533427200/1533513600

Use there.

Sale 6:

https://backpack.tf/profiles/76561198139190812#!/compare/1533600000/1533772800

Sold for 6 keys

Sale 7:

https://backpack.tf/profiles/76561198147318341#!/compare/1530662400/1530921600

https://backpack.tf/profiles/76561198024867201#!/compare/1530748800/1530835200

Untrace.

Sale 8:

https://backpack.tf/profiles/76561198044684270#!/compare/1531440000/1531526400

Untrace.

Sale 9:

https://backpack.tf/profiles/76561198063759209#!/compare/1530576000/1530748800

https://backpack.tf/profiles/76561198110254941#!/compare/1530576000/1530835200

SCM Sale, low / untrace

Sale 10:

https://backpack.tf/profiles/76561198045634257#!/compare/1530489600/1530748800

Untrace.

Sale 11, 12:

https://marketplace.tf/items/1183;5;u3006

Sold for 17.77 & 17.99 USD

Keys at 1.90, 1.87 USD

Totals are 9.35 & 9.62 keys

https://i.imgur.com/axAWq7y.png

Buyers up to ~7 keys,

Lots of sellers for 9, 10, 11 keys, most fairly recent.

https://backpack.tf/item/6759136533

https://backpack.tf/item/6254003901

https://backpack.tf/item/6276286318

https://backpack.tf/item/6257405859

https://backpack.tf/item/6252775691

Total sales @:

5, 6, 9.35, 9.62

Considering sellers at 9 keys, lets go with 9 - 9.5 keys.