Guess i'll do this one.

Credits to Shuffle Spy for the sales!

Quicksold for 16 Keys

http://backpack.tf/profiles/76561198144302129/#!/compare/1455868800/1455955200

Quicksold for 18 Keys

http://backpack.tf/profiles/76561198101622055/#!/compare/1455955200/1456041600

Quicksold for 20 Keys

http://backpack.tf/profiles/76561198080179568/#!/compare/1460160000/1460246400

Sellers:

http://www.tf2outpost.com/trade/28102499 21 Keys, young

http://i.imgur.com/N9nYg07.png http://backpack.tf/item/919432256 21.5 Keys, ~2 Weeks unsold(keep in mind that this is a bot that does automatic trades)

http://www.tf2outpost.com/trade/28099360 22 Keys, young

http://www.tf2outpost.com/trade/28099558 23 Keys, young

http://i.imgur.com/NtCnbtK.png 24 Keys, 2 MONTHS unsold

Even if 20 was a quicksell, the big amount of unsolds and the two sales and less support it massively. 20 Keys should be fine.

Additional Proof/Counter-Proof/Constructive Criticism/Feedback is always appreciated.