In this task you will be given a list of numbers and you need to find the mean (average) of that list. The mean of a list can be found by summing every number in the list then dividing the result by the size of that list. The output should be rounded to 3 decimal places.
[-63.664, 188.246, 114.276, 213.132, 192.142, 175.503, 34.958]