Dive summary:

• The iPad mini, iPhone 5, Kindle Fire HD and Nexus device launches did little to alter the amount of web traffic from May to November 2012.
• Chitika study said iOS had 67% of the browser share in November compared to 33% for Android devices. 
• A large portion of the difference is because the iPad leads to so much more web traffic than other tablets. 

From the article:

… Chitika also suggests that this data indicates mobile users stay loyal to the OS they’re already on when changing devices: Little change over a six-month period must cover upgrade points for a fair number of users, but people seem to be sticking with the OS they know, regardless of what changes are made in terms of hardware released. …