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: [-99.355, -3.837, 155.693, 130.002, 4.319, 184.828, 199.546]

81.599