Bestial rage only giving 12% despite having 30 rage.

I gave the node a try on druid.

I tried to see what my damage numbers were when I was at 0 rage versus 30 rage. My numbers went from 107 to 146. Not exactly 30 percent but we move on. After I had 30 rage, I took the skill and then checked the numbers again. It went to 163 (and I'm only worried about minimum numbers).

I was hoping that the skill would give me 12& per 10 rage. However, I am only getting 12% once reaching 10+ rage.