"Has the composition of the countries participating in the trial changed from the phase two trials to the phase three trial. For instance China is now part of the trial and I was wondering if it participated in the the phase two trials and to what extent.  I am loooking for  the exact percentages of the populations  comprising this and previous trials. TIA"

I don't know about exact percentages, but here is what can be found for trial study sites in news releases, publications and clinical trial listings for Phase 2 ASSERT, Phase 2 SUSTAIN, Phase 2 ASSURE, and Phase 3 BETonMACE. Note, see this post for BETonMACE.

ASSERT: (NCT01058018): US

SUSTAIN: (NCT01423188): South Africa

ASSURE: (NCT01067820): Argentina, Belgium, Brazil, Hungary, Netherlands, Poland, Russia, Spain

BETonMACE: (NCT02586155) Argentina, Belgium, Bulgaria, Croatia, Germany, Hungary, Israel, Mexico, Netherlands, Poland, Russian Federation, Serbia, Slovakia, and Taiwan/China.