Sale 1:

https://backpack.tf/profiles/76561198089253101#!/compare/1551052800/1551139200

https://backpack.tf/profiles/76561198280357510#!/compare/1551052800/1551139200

Sold for ~16 keys

Sale 2:

https://backpack.tf/profiles/76561198280357510#!/compare/1551225600/1551312000

https://backpack.tf/profiles/76561198119559226#!/compare/1490486400/1551312000

Sold for N&B Tree + ~7 keys in sweets

Tree Mini:

https://backpack.tf/suggestion/5cd90c67d38172175f68d3a2

Suggestion for 21 keys

https://bot.tf/stats/listings/4J28PWV4

B/O of 21 keys

Sale 3:

https://backpack.tf/profiles/76561198119559226#!/compare/1551398400/1551484800

https://backpack.tf/profiles/76561198892101673#!/compare/1551312000/1551484800

Sold for Lantern Buddy(20)

Sale 4:

https://backpack.tf/profiles/76561198892101673#!/compare/1551484800/1551571200

https://backpack.tf/profiles/76561198439167149#!/compare/1551484800/1551571200

Some amount of keys...

Sale 5:

https://backpack.tf/profiles/76561198439167149#!/compare/1551571200/1551657600

https://backpack.tf/profiles/76561198177279603#!/compare/1551398400/1551657600

Sold for 17 keys

Sale 6:

https://backpack.tf/profiles/76561198177279603#!/compare/1551398400/1551657600

https://backpack.tf/profiles/76561198161340716#!/compare/1551571200/1551657600

Sold for ~17 keys

Sale 7:

https://marketplace.tf/items/342;5;u11

$42.86 / $1.77 = 24.21 keys

Total sales @:

16, 17, 17, 20, 21, 24.21 keys

Listing for 19, for some months,

Buyers for 16 keys,

Taking 17 - 21 keys, conserving around unsold.