Marketplace sales:

https://marketplace.tf/items/30542;5;u58

Sale 1: $79.9 / $1.76 (7th Jan) = 45.39 ≈ 45 keys

Sale 2: $79.95 / $1.81 (26th Dec) = 44.17 ≈ 44 keys

Sale 3: $45.05 / $1.74 (23rd Nov) = 25.89 ≈ 26 keys

Sale 4: $85 / $1.72 (20th Nov) = 49.41 ≈ 49 keys

Sale 5:

https://backpack.tf/profiles/76561198166625691#!/compare/1547251200/1547424000

^

= 45 keys

Sale 6:

https://backpack.tf/profiles/76561198320651131#!/compare/1545955200/1546128000

^

= ? (unavailable)

Sale 7:

https://backpack.tf/profiles/76561198035280371#!/compare/1547856000/1547942400

= 39 keys

Sale summary: 45, 44, 26, 49, 45, 39

Conclusion: range should be 39-49 keys, Sale 3 and Sale 4 is an outlier.

Notes:

- Sales from this (https://backpack.tf/item/7347031858) were not included (except for Sale 6) because comparison links did not clearly display what was exchanged.