Counting a percentile based on conditional column

Hello,

I have a table with a list of states and time entity spent in these states.

I need to calculate a percentile for each state from this table.

Is there any way to make something like this:

Let's put it rough 

"if State == "New"; percentile.exe([TimeInState];075)"

Or maybe I need to transform this table somehow.

The table looks like this: