Take a look at the financial reports issued by the major oil companies, for example: in 1999, refinery profit margins were about 5¢ or 6¢. They were already making money back then with those kinds of margins. So, one can assume that 5¢ or 6¢ is a reasonable profit. However, it is when that starts to rise that profits become excessive and, right now, profit margins were about 25.7¢ in May. I believe that can certainly be deemed excessive.
On June 13th, 2007. See this statement in context.