The attribute appears on the Resource- Allocations: Summary page as well as Team Staff and Detail pages with a column header named 'Average Allocation %' when added to portlet layout configuration.
The values are not the same as the 'Default Allocation %' (formerly known as '% Allocation') attribute.
Steps to configure portlet layout from Resource->Allocations:
How is the Average Allocation Percent (%) field calculated?
It is the average percent over the effective duration of the allocation. It matches the 'Default Allocation %' if there are no exception allocation segments defined. Therefore, it is the average of all the allocation segment percentages for each investment in the Resource Project Allocation portlet. To change allocation segments, click on the 'properties' icon for one of the rows within this portlet.