The price drop could possibly have been caused by the recession which was at its worse in 2009. More drivers and motorcyclists would therefore try to stay off the road to save as much money as they can.
Natural disasters caused changes in fuel prices. The BP spillage in 2012 caused low confidence among customers using BP and increased the price of fuel due to this. As well as this, the amount of countries that produce crude oil has an effect on the prices. Iraq and Iran currently have lots of oil making their oil a lot cheaper to buy than other countries that have less fuel.