Marketplace tf Proof: https://marketplace.tf/items/tf2/31112;5;u151

Sold on November 6, 2020:

$12.6/$1.78 = around 7.08 keys

Sold on November 7, 2020:

$7/$1.81 = around 3.87 keys

Sold on November 9, 2020:

$11.6/$1.79 = around 6.49 keys

Sold on November 10, 2020:

$11.6/$1.78 = around 6.52 keys

Sold on November 11, 2020:

$12.1/$1.79 = around 6.76 keys

Sold on November 12, 2020:

$12.1/$1.78 = around 6.80 keys

Sold on November 14, 2020:

$12.6/$1.78 = around 7.08 keys

Sold on November 15, 2020

$15.99/$1.76 = around 9.09 keys

Take the average of all of the key prices and you get 6.71125 keys.

I am taking 6.71 keys for the low value, and 7 keys for the high value because many people are selling on backpack.tf classifies for around 7 keys as of 11/17/2020.