In the tabs of skills and standards you can configure different options for the calculation such as adding a column with the average calculation, to do this you must press the right button (long click in the Apps) on the corresponding tab (skills or standards) and select the Set up option.
This will open a modal window with different options for calculating skills and standards.
In the option "Select tabs for the calculation" you can select the tabs and columns that you want to include in the calculation of the skills and standards, although by default they would all be selected. This way, if for example you have tabs for each quarter, you can get the calculations only from those tabs and columns of the current quarter.
To calculate the average you must check the box "Add average column", then an option will be shown to configure the columns of skills or standards that you will take in account in theaverage calculation.
The columns included in the calculation will be weighted, with all the columns having the same percentage weight by default, although these values can be modified if desired.
Also from this configuration window you can activate the "Show average of each column" box, this will make a new row appear at the end that contains the average for each of the columns.
Finally, by pressing the Save button will be shown all the changes made.