Don't hold back..

Sale 1: Unknown

https://backpack.tf/profiles/76561198045775820#!/compare/1585094400/1585180800

https://backpack.tf/profiles/76561198070983297#!/compare/1426748400/1586995200

Sale 2: Sold for keys, not sure how many

https://backpack.tf/profiles/76561197971654911#!/compare/1586563200/1586649600

https://backpack.tf/profiles/76561198057604391#!/compare/1586563200/1586649600

Sale 3: Sold for 12 keys

https://backpack.tf/profiles/76561198052756454#!/compare/1586476800/1587254400

https://backpack.tf/profiles/76561197971654911#!/compare/1586390400/1586563200

Sale 4: Unknown

https://backpack.tf/profiles/76561198850274253#!/compare/1588636800/1588723200

https://backpack.tf/profiles/76561198022897937#!/compare/1588723200/1588809600

Buyout was 13 keys + 52.11 refined

https://bot.tf/stats/listings/4P0O7OKE

Sale 5: Unknown

https://backpack.tf/profiles/76561198337734785#!/compare/1586304000/1586390400

https://backpack.tf/profiles/76561198206072125#!/compare/1586304000/1586390400

Buyout was 17 keys

https://bot.tf/stats/listings/M0O72882

Sale 6: Sold with other unusuals for 122 keys

https://backpack.tf/profiles/76561199005639502#!/compare/1582675200/1582761600

https://backpack.tf/profiles/76561198876179362#!/compare/1582588800/1582848000

Sale 7: Unknown

https://backpack.tf/profiles/76561198432461884#!/compare/1583452800/1583539200

https://backpack.tf/profiles/76561198066813088#!/compare/1583366400/1583452800

Sale 8: Unknown

https://backpack.tf/profiles/76561198046779947#!/compare/1583366400/1583625600

https://backpack.tf/profiles/76561198432461884#!/compare/1580515200/1583366400

Sale 9: Marketplace

https://marketplace.tf/items/tf2/390;5;u56

35 on May 26, 2020 (35/1.94 = 18.04 rounding to 18 keys)

Classifieds:

https://gyazo.com/a7284daa6634be62bcb45ccd764a60ba

Sales at 12 and 18. Sellers are at 17 and 18. Excluding 18. Taking 12 keys here.