How to filter products by discount percentage with url parameters

[Fabio Manzo]

I'd like a way to add a parameter in the URL to filter products by discount percentage like  do with the price: 

https://pescatorehome.com/12-pigiami-e-vestaglie?q=Prezzo-€-2-209

The upper query works, the bottom one does not, why?

https://pescatorehome.com/12-pigiami-e-vestaglie?q=Discount-%-40-80

Whit this lates query, I'd like to see only the products that have a discount from 40 to 80 %. How can I achieve this using URL parameters?

 

Thanks