Selling For 15 Keys:

3x http://backpack.tf/classifieds/search/id/52c926864cd7b8304b8b4568

http://www.tf2outpost.com/trade/19942065 - 2 Parts

http://www.tf2outpost.com/trade/19937623

http://www.tf2outpost.com/trade/19784842 [1 Week]

http://www.tf2outpost.com/trade/19928220

Unsold For 16 Keys:

http://www.tf2outpost.com/trade/17276740 [4 Months] - 2 Parts

http://www.tf2outpost.com/trade/19901644 [2 Days]

http://www.tf2outpost.com/trade/19543501 [3 Weeks]

http://www.tf2outpost.com/trade/19876779 [4 Days] - 15 Keys + 3 Ref

Conclusion:

-Plenty of 15 keys sellers

-some 15 keys are still young so range is still there

-there is 1 in range 15 keys + 3 ref so range is still there

-16 keys is hard to sell so i'm guessing the price will go down again in the next week or 2

-last updated price change 2 months ago

feel free to leave a comment :)