Surprising Results on BPMN Self-Test

I am a little surprised at the scores on my BPMN self-test. Ten questions, four diagrams each, one of which is the correct answer. The scenarios are typical from real-world processes, and most of the patterns should be used routinely in process models. A couple of questions are a little hard, but I would have thought that more people understood the basic usage of timer, message, and error events, event gateways, loop vs MI activities, etc. The highest score so far is 80 (out of 100). (You can take the test more than once but I'm only tabulating the first one.) Here is the histogram of scores so far:

[Updated Jan 5, 2010, 8:47am PT]

Oh well... The goal was to get people to think about training. I guess it should. Click here to take the test.