Here is an analysis of Kickstarter projects for games 2012:
The final few slides provide a percentage split per game category, and interesting for you is a comment on slide 15 - "RPGs and Adventure games are still very much dominating"
Edit: Another article http://www.vgchartz.com/article/250252/weekly-sales-analysis-30-june-2012-spec-ops-spider-man/ for global sales across all platforms, compiled during 2012, shows 4 of the top 5 slots are held by RPG and Adventure games.
Edit2: Alexander, if time is no question for you, then please make use of "App Annie" (google it), and Distimo provide reports too. You could contact Distimo or AppAnnie via email and ask them a question or two on this matter. Good luck!