Okay...

Sale 1: Unknown

https://backpack.tf/profiles/76561198337734785#!/compare/1583193600/1583280000

https://backpack.tf/profiles/76561198191786397#!/compare/1590883200/1580860800

Sale 2: Unknown

https://backpack.tf/profiles/76561198247144444#!/compare/1590710400/1590883200

https://backpack.tf/profiles/76561198088250438#!/compare/1590796800/1589673600

Sale 3: Unknown

https://backpack.tf/profiles/76561198850274253#!/compare/1589155200/1589241600

https://backpack.tf/profiles/76561198008931439#!/compare/1582934400/1589500800

Sale 4: Unknown

https://backpack.tf/profiles/76561198020673987#!/compare/1588204800/1588291200

https://backpack.tf/profiles/76561198850274253#!/compare/1588204800/1588291200

Sale 5: Unknown

https://backpack.tf/profiles/76561198041638247#!/compare/1585699200/1585785600

https://backpack.tf/profiles/76561198028422102#!/compare/1583366400/1586131200

Sale 6: Unknown

https://backpack.tf/profiles/76561198986747837#!/compare/1586649600/1586736000

https://backpack.tf/profiles/76561198134512931#!/compare/1586649600/1586563200

Sale 7: Unknown

https://backpack.tf/profiles/76561198134512931#!/compare/1587772800/1587859200

https://backpack.tf/profiles/76561198068219260#!/compare/1579564800/1587859200

Sale 8: Bulk

https://backpack.tf/profiles/76561198270949034#!/compare/1587859200/1587945600

https://backpack.tf/profiles/76561198120672630#!/compare/1587772800/1587859200

Sale 9, 10, 11 & 12: Marketplace

https://marketplace.tf/items/tf2/30390;5;u58

https://backpack.tf/item/7957085046

44.88 on March 28, 2020 (44.88/1.69 = 26.55 rounding to 27 keys)

45 on April 3, 2020 (45/1.7 = 26.47 rounding to 26 keys)

2 sold for 45 on April 4, 2020 (45/1.72 = 26.16 rounding to 26 keys)

Classifieds:

https://gyazo.com/4410d5e835a47443abbf76aa59ec472d

Sales are at 26, 26, and 27. Taking a range of 26-27 keys here.