How many CDs are in each of The Story of the World audiobooks?

The Story of the World audiobook CDs are in sleeves and packaged in a cardboard box along with an information booklet. 

Vol. 1 - 7 CDs
Vol. 2 - 9 CDs
Vol. 3 - 9 CDs (Original and Revised)
Vol. 4 - 11 CDs (Original and Revised)