Befuddling patent numbers

I was having a conversation with a European investor today, and the subject of patents came up.  Specifically, the question of which global region is the source of the most clean energy innovation, as measured by patents.

Simple question to answer, right?  Except that my quick googling for the answer has left me completely befuddled.

In the OECD report linked to here (note: opens pdf), specifically on pg. 21, it indicates that in 2005 the EU accounted for 37% of renewable energy patents, with the U.S. and Japan lagging at around 20% each.

In the Lux Research report linked to here, they suggest that the U.S. leads in cleantech patents issued, with 46% of the total for 2006.

And for good measure, in this additional quarterly clean energy patent survey, while they don't track overall regional totals it would appear that Germany regularly falls behind even Michigan when it comes to clean energy patents!

What's going on here??  Is Europe way ahead in clean energy patents, as the investor I was speaking to claimed today, or does the EU's powerhouse Germany fall behind even Michigan when it comes to clean energy innovation?

Color me confused.

In other news and notes:  Here's a great blog on cleantech IP issues...  Here's Kanellos on some other weirdness in the cleantech patent tallies...  Here are some good thoughts from Dan Goldman on the Clean Energy Accelerator Corp...  And finally, congrats to Peter Rothstein on his new gig with the NECEC, where he'll be working on (among other things) a pretty interesting challenge with the Clean Energy Innovation Consortia Project (first task: come up with a catchier acronym).