The mean, or average, of a list of numeric observations is their sum divided by their count. section 5.9.3
Average a list in Python
For a list named temperatures, calculate the mean with mean_temp = sum(temperatures) / len(temperatures). section 5.9.3
The values must support arithmetic: missing entries or percentage strings are read as strings, so clean or handle them before calculating an average. section 21.4.1
