How are Thomson Reuters League tables calculated?

this might be a very basic question, and i apologize before anyone starts lashing, but i was wondering how are the league tables drawn?

i know it's deal value, but what deals does it take into account? Most of the deals that are reported in NY dealbook or bloomberg have been going on for sometime, and it takes time for them to complete.

Did Thomson Reuters , atleast the one for 1st Quarter 2011, take those in account, or does it only consider deals announced for the first time in 2011?

I feel that Thomson Reuters has access to deals that public does not know about until they are nearing completion, because some banks such as DB have been involved in a lot of mega deals since this year yet they trail Citi, CS when it comes to Global M&A advisory.

It would be great to get clarification. Thanks a lot guys!