When applying any type of filter to a report or view, there should be a sub total and a total provided. So if the grand total is 1,000 and we filter out items that are worth 100, then we should see a sub-total or filtered total of 900 as well as a grand total of 1,000. The percentages of each item should be impacted the same way. % of grand total and % of sub total. This should be available on every report and every metric.