we got a bunch of marketplace sales, so lets throw up the graph for key prices right away for referencing here: https://marketplace.tf/items/tf2/5021;6

Sale 1: March 6th 2020, 69.99$ Keys were 1.71, equaling 40.9, rounding to 41.

Sale 2: March 5th 2020, 45.16$ Keys were 1.69, equaling 26.7, rounding to 27, ignoring due to buy orders being at 32 keys.

Sales 3&4: Feb 2nd 2020, 62.00$ Keys were 1.78, equaling 34.8, rounding to 35.

Sale 5: Dec 28, 2019 at 42.56$ Keys were 1.79, equaling 23.77, rounding to 24, ignoring due to buy orders.

There's an item sale on Dec 15th, but I'm not going to count it as a sale because of its age.

So we have: 41, 35. A healthy range of 35-41.

As always feel free to correct or advise in the comments