[Koha] Looking for a bit of report help

I'm looking for some help with reports that require more math than my brain can handle. #1: circulation by % coll code within a date range [50% of DVDs circulated] I have this one: http://wiki.koha-community.org/wiki/SQL_Reports_Library#Percentage_of_circs_... I'm not sure how to alter it to show the percentage of the DVDs in the collection instead of the percentage of all check outs. #2: DVDs circulating 50% of total DVDs where DVD is a collection code This might be the same as the above ... unless you all read it differently than me. Thanks in advance, Nicole