Definition: 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.
Input: [78.459, 194.537, -6.872, -79.655, -18.061, 103.494, 44.622, 34.481, 220.585]

63.51