Fuel prices became a major concern in the 1970s, and have gained attention again. Fuel is only marked up about 5-9% at retail outlets. Fuel prices are influenced by taxes, marketing costs, distribution costs, geographical region, refinery productivity, supply, demand, crude oil prices, markup (i.e., profits), investor speculation of future prices, and world events. Every year more and more vehicles are put on the highways, increasing the demand for fuel. If the supply of fuel decreases and fuel demand increases, prices will surely rise.