Summarizing Node Availability Using Custom Properties

I've built a report to work around the flaw in group availability.  Basically, I needed to provide group availability as a measure of service availability for groups of nodes.  I used custom properties to allow me to build group reports as using the groups plus the nodes meant some custom SQL that was over my head.  I've built a nice report that gives all nodes for each of my three custom properties (class_group, hardware_group, service_group) where the availability is less than 100% for the previous month.

Now the hard part.

Any ideas how I can build a summary, by custom property (remembering that each custom property has a series of values to group nodes together), for availability?  Basically, I'm looking for a report that would list something like:

Class_Group

     Property_1     97%

     Property_2     98%

     Property_3     100%

Hardware_Group

     Property_1     97%

     Property_2     98%

     Property_3     100%

I think I need to go tap a SQL resource to make this work, but I thought I'd ask if anyone else had worked through this problem already.

Be well.