Generating table of depreciation/amortization values between predefined values

Hello all,

I'm having some trouble to calculate/generate a new monthly table with the right diminishing values. Here below example data containing 1 object. The value of object 1 is predefined on specific dates one year ahead of the previous predefined value. So in this example object 1 is worth 52.000 on july 2020 and 41.000 on july 2021. 

I want to create a new table that calculates the table on a monthly basis. Between july 2020 and july 2021 the depreciation is 916,67 per month ((52k-41k) /12, but i'm having an issue with generating a new table because in the period of july 2021 and july 2022 the depreciation is not the same -> (41k-28k)/12 = 1083,33. Objects data are always predefined on specific dates in the future and i'm not sure how to get the right calculation for that. I'm hoping someone can help me out with this.

Kind Regards, Muffin