I'm sure its easy but....

so you have 9 groups?  

You can combine the groups.  So really depends on what you want to know.  I would try lots of things.  

Maybe create 3 more groups of Y, N, Maybe (in a new library?) and drag and drop all of the 3 matching  into that group, so you end up with how many total had 1 or more Y (or N or Maybe) “votes”.  Putting them in a new library means you can see how many times, and then remove duplicates.  rmoving duplicates shouldn’t remove any from the group and you should be left with a useful list.  You can also do this by creating a group from groups and combining groups in the same library (this is a smart group type) (right click in the groups part of the menu and choose “create from groups”  1-Y or 2-Y or 3-Y). 

To find out the set they all agreed should be Y or N or maybe, you can combine groups, so look for those that all three agreed should be in a group  (1-Y and 2-Y and 3-Y). 

I usually freeze a smart group like this by dragging the whole set into a new hard-wired group, so after removing duplicates, it won’t change when you delete some copies.