Why gas cost so much?

That structure is pretty incredible. I don't want to get into why gas is so high, I am not smart enough to figure out all the nuances that contribute to it. What I want to know is, WHY DOES DIESEL COST MORE??????? It takes half the refining to produce diesel yet it costs more than premium...that my friends is price gouging and it sucks...LOL, every vehicle I own is diesel including a boat.