Mini.

Sale 1: https://backpack.tf/profiles/76561198189106033#!/compare/1569628800/1569715200

https://backpack.tf/profiles/76561198253483866#!/compare/1569628800/1569715200

Qs, 17 pure and ref.

Sale 2: https://backpack.tf/profiles/76561198253483866#!/compare/1569801600/1569888000

https://backpack.tf/profiles/76561198420739463#!/compare/1569801600/1569888000

Qs, 19 pure.

Sale 3: https://backpack.tf/profiles/76561198071588645#!/compare/1570233600/1570320000

https://backpack.tf/profiles/76561198253483866#!/compare/1570233600/1570320000

Sold for a clean Vivid Plasma Pyro's Beanie (16 keys) + 3 pure.

16 + 3 = 19

Sale 4: https://backpack.tf/profiles/76561198253483866#!/compare/1570233600/1570320000

https://backpack.tf/profiles/76561198024805594#!/compare/1570233600/1570320000

?

Sale 5: https://backpack.tf/profiles/76561198024805594#!/compare/1570406400/1570492800

https://backpack.tf/profiles/76561198061489334#!/compare/1570492800/1570579200

Sold for a clean Starstorm Slumber Airdog (18 keys)

Sale 6: https://backpack.tf/profiles/76561198002757046#!/compare/1571270400/1571356800

https://backpack.tf/profiles/76561197964171516#!/compare/1571270400/1571356800

Qs.

Sale 7: https://backpack.tf/profiles/76561197964171516#!/compare/1572480000/1572566400

https://backpack.tf/profiles/76561198112500795#!/compare/1572480000/1572566400

Sold for a Strange Kritzkrieg (20 keys)

Sale 8: https://backpack.tf/profiles/76561198112500795#!/compare/1572825600/1572912000

https://backpack.tf/profiles/76561198316961222#!/compare/1572825600/1572912000

Resold for 14? God hot damn.

Sale 9: https://backpack.tf/profiles/76561198011168187#!/compare/1570406400/1570492800

https://backpack.tf/profiles/76561198097271466#!/compare/1570406400/1570492800

Qs for 15.

Sale 10: https://backpack.tf/profiles/76561198097271466#!/compare/1572652800/1572739200

https://backpack.tf/profiles/76561198121096537#!/compare/1572739200/1572825600

Qs for 17.

Sale 11: https://backpack.tf/profiles/76561198121096537#!/compare/1573776000/1573948800

https://backpack.tf/profiles/76561198110037051#!/compare/1573862400/1573948800

Sold for a clean Nuts n' Bolts Modest Pile of Hat (21 keys) + ~3 in sweets, buyout was 20: https://bot.tf/stats/listings/Y5R73935

Sale 12: https://backpack.tf/profiles/76561198165205268#!/compare/1569024000/1569110400

https://backpack.tf/profiles/76561198026012936#!/compare/1568851200/1569110400

Qs, 17 pure + ref.

Sale 13: https://backpack.tf/profiles/76561198026012936#!/compare/1568851200/1569110400

https://backpack.tf/profiles/76561198072181775#!/compare/1569024000/1569110400

?

Sale 14: https://backpack.tf/profiles/76561198072181775#!/compare/1569283200/1569801600

https://backpack.tf/profiles/76561198042982540#!/compare/1569715200/1569801600

?

Sale 15: https://backpack.tf/profiles/76561198042982540#!/compare/1569801600/1569888000

https://backpack.tf/profiles/76561198180923509#!/compare/1569801600/1569888000

?

Sale 16: https://backpack.tf/profiles/76561198180923509#!/compare/1569974400/1570060800

https://backpack.tf/profiles/76561198218095591#!/compare/1570060800/1570147200

Qs.

Sale 17: https://backpack.tf/profiles/76561198218095591#!/compare/1570406400/1570492800

https://backpack.tf/profiles/76561198189106033#!/compare/1570406400/1570492800

Sold with 1 key for a Strange Specialized Killstreak Australium Knife (17.5 keys)

17.5 - 1 = 16.5 (17)

Sale 18: https://backpack.tf/profiles/76561198189106033#!/compare/1570665600/1570838400

https://backpack.tf/profiles/76561198089253101#!/compare/1570665600/1570752000

Qs.

Sale 19: https://backpack.tf/profiles/76561198082451883#!/compare/1573084800/1573171200

https://backpack.tf/item/7957558253

https://marketplace.tf/items/tf2/253;5;u10

36.08/1.79 = 20

Sales: 17, 19, 19, 18, 15, 17, 20, 17, 17 and 20. Classies: https://i.imgur.com/9HajgWb.png. Going with a range of 17-20.