Pivot table for staffing models

[ammartino44]

Hello. I have attached a file for staffing models. I have a bunch of different departments, and a bunch of dates. I would like to do two things:

1) Create a max headcount for each year (looking at the sum of all departments for EACH month), so each year would have one max value. When I try to do max it gives me just the max for one department. I want the max of the sum. How can I do this?

2) I use sum to get the values for each month (sum of all departments). How can I get the grand total to show the average of these sums?

Spreadsheet attached.