Add choice of pencentage in project states dropdowns

We would like to automate the pencentage of completion of a task or project thanks to the states, instead of selecting for instance 20%, 75% or 100%.

EX : if I select the state "Done", the percentage goes automaticaly to 100%.

Could it be posible to give the choice to add a specific percentage to a state when configurating our dropdows?

Thank you