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.

Example Input: [9.828, 248.054, 20.871, 99.749, 52.797, -86.856, 65.438, 53.627]
Example Output: 57.939

Example Input: [22.306, 72.768, 218.947, 52.973, 100.121, 157.59, -92.109]
Example Output: 76.085

Example Input: [195.18, 220.835]
Example Output:
208.008