Filter Column by top percentage rank

[smore]

'Table'[Product]

'Table'[Size] 

I have these columns as "Values" in a visualizations table. I am trying to filter by percentage of top size (largest to smallest). 

Example Slicer Values: 5%, 10%, 20%, 30% 

So, if I selected 5% the visualizations table would only show the top 5% largest products by size.

I created a calculated column [Size Ranked] = RANKX('Table',[Size])  which ranks by size. 
I thought I could do something like Filter([Size Ranked] < COUNTROWS('Table')* 0.05)) but I get the error:
"The expression refers to multiple columns. Multiple columns cannot be converted to a scalar value."

[amitchandak · Accepted solution]

@smore , I think you need percentile with what if parameter

https://blog.enterprisedna.co/implementing-80-20-logic-in-your-power-bi-analysis/
https://forum.enterprisedna.co/t/testing-the-pareto-principle-80-20-rule-in-power-bi-w-dax/459

https://docs.microsoft.com/en-us/power-bi/desktop-what-if