You've got about as close as you can get with that.
MC searches and expressions cannot count files, only compare tags within single files.
You
can get a visual representation though, if that helps you any?
Choose an audio view that contains an Album pane and select it.
In the view header, hover the mouse over the view title, just to the left of that little black arrow, and at the top of the list that pops, you should see "Pane" followed by the rest of the pane labels in your view scheme... click on Album
Hover the mouse in the same place again, click on "Details"
The name column you see there refers to each of your albums.
Right click on the column header to the right of the "Name" column and follow the "Columns" entry, pick "Number Plays" from the list to add that column next to the name column.
What you see there in the Number Plays column is the average number of plays for each album.
Click the column header to sort by it.
I'm not sure if this suggestion could help you or not, have a read and add any thoughts you may have on the subject...
http://yabb.jriver.com/interact/index.php?topic=45062.0-marko.