Yes, you are right. This graph has the lower duty cycle on the side that states rich. I think it is a mistake from its creator (whether the graph is right or wrong I am not to be credited, I just borrowed from one of the forum's member's website). According to the manual a low duty cycle means a rich mixture. The article from Stevebfl in the DIY section "Evaluating Electronic Engine Controls" mentions a duty cycle of 35% as rich.
Quote: "The value of 38% indicates a rich reading".
The fact that your duty cycle drops when turning CCW is waaaaay over my head.
Experts, please take me out of my ignorance, explain this matter.