Creating dynamic Power BI Parameters for Week on Week comparisons

Hi, its been a short while since I've been using What-if Parameters in Power BI. 

Though I am struggling when I want to make week on week/ month on month comparisons, in cases where I require the parameter value to be different across weeks/months. 

Below is an example: 

Expected Sales Parameter = 2 for Week 1

                                             3 for Week 2 and so on.

*Expected Sales is manually inputted by the user in the parameter filter. 

Basis Stock and Sales I am computing a 'Cover':

Cover = Stock / (Sales * Expected Sale Factor)  

Eg. Wk 1, Product A, Cover = 100/ (50 * 2) = 1. 

Note the nature of Expected Sales (and even discounts in other cases) is not static week on week (or month on month). 

As of now, as a way around this, I am looking at my data by selecting only one week and setting the Expected Sales parameter to give me the cover of that week. 

However, this means that I cannot compare the Cover of current week and previous, or create any trend visualisations on the Cover. 

Is there a way around using parameters or any other solution.  Thanks!