The government researches the gasoline price every month. The following figure shows the changes in the gasoline price from 1966 to 2014 July.
Figure : Gasoline price of one litre in every July from 1966 to 2014 (unit : yen)
The 1973 oil crisis raised the gasoline price by 50%.
There was Iranian revolution in 1979. After the revolution, the gasoline price was pushed up.
From 2003 to 2008, the third wave of the oil crisis was coming. It caused by complicated factors.
Source is Statistics Bureau.