Average monthly spending in Budget

When I plan my budget for the next quarter/year I like to use the real yearly/quarterly spending as a base to predict my monthly spending. 

 

By now, I have to take the spending for the whole year and manually divide it in the calculator to get the average monthly amount.

 

I'd like to have the table/additional number that gives me the average spending/income in each category in the reporting period I've chosen.