I have a list of numbers not in any particular order,

1, 33, 5 , 15, 22, 489, 100, 56, 17, 109, 367, 54, 20

I want to throw out the top 10% and botton 10% and do an average of the
remaining numbers, how do I do this?

p.s. I just provided 10% as an example, I need to be able to change this to
any percentage.