Resuggestion, thanks to K1ng for the info!

Sale 1:

https://backpack.tf/profiles/76561198061108999#!/compare/1535932800/1536019200

https://backpack.tf/profiles/76561198063140324#!/compare/1535587200/1535932800

Sold for CPS Grenadier

Grenadier Mini:

https://backpack.tf/suggestion/5badb36744325a55bc51b5e1

Suggestion for 12 keys

Sale 2:

https://backpack.tf/profiles/76561198137934248#!/compare/1534204800/1537920000

https://backpack.tf/profiles/76561198062010270#!/compare/1525392000/1534809600

Transfer?

Sale 3:

https://backpack.tf/profiles/76561198319462978#!/compare/1533513600/1533772800

https://backpack.tf/profiles/76561198377163339#!/compare/1533686400/1535500800

Untrace.

Sale 4:

https://backpack.tf/profiles/76561197964171516#!/compare/1533686400/1533772800

https://backpack.tf/profiles/76561198291522880#!/compare/1533772800/1533859200

Sold for Searing Birdcage

Cage Mini:

https://backpack.tf/suggestion/5badbb6544325a5a5a67a377

Suggestion for 12.5 keys

Sale 5:

https://backpack.tf/profiles/76561198291522880#!/compare/1533772800/1533859200

https://backpack.tf/profiles/76561198437172792#!/compare/1533772800/1533859200

Sold for Atomic HFOHA(11.5)

Sale 6:

https://backpack.tf/profiles/76561198306872661#!/compare/1532908800/1532995200

https://backpack.tf/profiles/76561198043826027#!/compare/1532908800/1533081600

Sold for 9 keys

Sale 7:

https://backpack.tf/profiles/76561198043826027#!/compare/1533081600/1533168000

https://backpack.tf/profiles/76561198129253150#!/compare/1533081600/1533168000

Bulk / untrace

Sale 8:

https://backpack.tf/profiles/76561198129253150#!/compare/1533081600/1533168000

https://backpack.tf/profiles/76561198153011059#!/compare/1535760000/1535846400

Can only trace 4 keys

Sale 9:

https://backpack.tf/profiles/76561198153011059#!/compare/1535760000/1535846400

https://backpack.tf/profiles/76561198444734571#!/compare/1531440000/1533168000

Untrace.

Sale 10:

https://backpack.tf/profiles/76561198444734571#!/compare/1533168000/1533340800

https://backpack.tf/profiles/76561198295160385#!/compare/1533254400/1533340800

Sold for 11 keys

Sale 11:

https://backpack.tf/profiles/76561198295160385#!/compare/1533254400/1533340800

https://backpack.tf/profiles/76561198119122799#!/compare/1533340800/1533427200

Untrace

Sale 12:

https://backpack.tf/profiles/76561198119122799#!/compare/1533340800/1533427200

https://backpack.tf/profiles/76561198132538422#!/compare/1533254400/1533427200

Sold for 11 keys

Sale 12:

https://backpack.tf/profiles/76561198132538422#!/compare/1533513600/1533859200

https://backpack.tf/profiles/76561198214364347#!/compare/1533600000/1533859200

Sold for Planets Eyewear(15) + negligible sweets

Sale 13:

https://backpack.tf/profiles/76561198214364347#!/compare/1533945600/1534032000

https://backpack.tf/profiles/76561198418566428#!/compare/1533859200/1533945600

Sold for DP Burglerre

Burglerre Mini:

https://backpack.tf/suggestion/5badcef644325a61942f7a02

Suggestion for 11.5 keys

Sale 14:

https://backpack.tf/profiles/76561198418566428#!/compare/1534032000/1534291200

https://backpack.tf/profiles/76561198173389367#!/compare/1534118400/1534291200

Untrace.

Sale 15:

https://backpack.tf/profiles/76561198173389367#!/compare/1535155200/1535241600

https://backpack.tf/profiles/76561198345326844#!/compare/1533945600/1535241600

Sold with 1 key for DBD Mullet(16)

Total is 15 keys

Sale 16:

https://backpack.tf/profiles/76561198345326844#!/compare/1535241600/1535328000

https://backpack.tf/profiles/76561198074879249#!/compare/1534982400/1535328000

Sold for Stormy Shako(13.5)

Sale 17:

https://backpack.tf/profiles/76561198074879249#!/compare/1535500800/1535760000

https://backpack.tf/profiles/76561198099149103#!/compare/1535500800/1535846400

Sold for Aussie Grenade Launcher(~13) + ~3 keys in sweets

Total is 16 keys

Sale 18, 19:

https://marketplace.tf/items/30978;5;u18

Sold for 28, 20 USD

Keys at 1.90, 1.88 USD

Totals are 14.74, 10.64 keys

Total sales @:

9, 10.64, 11, 11, 11.5, 11.5, 12, 12.5, 13.5, 14.74, 15, 15, 16 keys

Unsold for nearly a month at 14 keys

https://i.imgur.com/B2EDnvr.jpg

https://backpack.tf/item/6753011667

Calling above 14 outliers

K1ng's Part:

Another sale at 12 keys here:

https://backpack.tf/profiles/76561198334598690#!/compare/1533074400/1533160800

Would be fair to ignore the sale at 9, considering that you are leaving out four sales above 14, and it doesn't seem to be a common trading point. 11-14 should work.