I think those market share numbers are suspicious.. according to rackspace they had 1.3b in sales of private cloud and public cloud services in 2012: http://ir.rackspace.com/phoenix.zhtml?c=221673&p=irol-ne...

So either the total is more than 100% market share for the 3, or those numbers or wrong.

Edit: added "in 2012" for rackspace financials