From wordpress.com which takes from w3techs.com – WordPress is used by 60.8% of all the websites whose content management system we know. This is 23.6% of all websites.
Also from w3techs.com – Joomla is used by 7.4% of all the websites whose content management system we know. This is 2.9% of all websites.
Market share is with WordPress. Infact trend is that Joomla is slowly declining while WordPress is gaining a steady percentage of growth. This may change as efforts are being made to make Joomla more accessible to all. More on this later.