Aggregate and trend filtered reports

In SiteCatalyst I miss a really basic functionality, and that is to be able to aggregate and trend filtered reports. I can't seem to find a way to do this, but at the same time it surprises me that it is not possible. I.e. if I look at the report for natural search keywords, and filter it for the word "shoes", I would get a lot of different variations of keywords that contain "shoes". When I trend this report, it will show me the top five keywords/phrases containing "Shoes". What I want to see is the total of all keywords/phrases containing "shoes" trended, but this does not seem to be possible. Therefor I would like to see the possibility to filter, aggregate and trend reports (which is a really basic feature that one would expect). Please apologize if this is possible already, but I couldn't find out how to do it