Resuggestion, thanks to Foamy, Blaze & Mindacos for the info!

Sale 1:

https://backpack.tf/profiles/76561198136987862#!/compare/1534809600/1534982400

https://backpack.tf/profiles/76561198267963372#!/compare/1534809600/1534896000

Untrace.

Sale 2:

https://backpack.tf/profiles/76561198267963372#!/compare/1534982400/1535068800

https://backpack.tf/profiles/76561198267963372#!/compare/1534982400/1535068800

Sold for DBD Stormin'

Stormin Mini:

https://backpack.tf/suggestion/5bc3eba144325a6a4b7de0a8

Suggestion for 14 keys

Sale 3:

https://backpack.tf/profiles/76561198292848229#!/compare/1535155200/1535241600

https://backpack.tf/profiles/76561198019257028#!/compare/1535155200/1535241600

Sold for Aces Soldered(14.5) + 1 key in sweets

Total is 15.5 keys

Sale 4:

https://backpack.tf/profiles/76561198019257028#!/compare/1536796800/1536883200

https://backpack.tf/profiles/76561198155502977#!/compare/1536796800/1536883200

Sold for Eerie Bolted Birdcage + negligible sweets

Use there.

Sale 5:

https://backpack.tf/profiles/76561198161216801#!/compare/1534723200/1534809600

https://backpack.tf/profiles/76561198089253101#!/compare/1534723200/1534809600

Sold for Strange CTFL Sinner

Foamy's Part:

the seller countering the data point at 16 sold, providing a solid middle ground for it to be included.

https://backpack.tf/profiles/76561198337734785#!/compare/1539561600/1539648000

https://backpack.tf/profiles/76561198037041957#!/compare/1539216000/1539648000

Mindacos' Part:

Sale 2 is wrong, the DBD Sultan added 4 Keys for the DBD Norman: https://backpack.tf/profiles/76561198292848229#!/compare/1534982400/1535068800

That's going to make Sale 2 10 Keys, which is an outlier.

The "additional data point" is a sale at 15 that should be included, so this ends up being 15-16.

Blaze's Part:

https://marketplace.tf/items/403;5;u62 - sold for $29.99

Taking 15 - 17 keys