In the 1970s, Brunei invested sharply increasing revenues from petroleum exports and maintained government spending at a low and constant rate. Consequently, the government was able to build its foreign reserves and invest them around the world to help provide for future generations. Part of the reserve earnings were reportedly also used to help finance the government's annual budget deficit. Since 1986, however, petroleum revenues have decreased, and government spending has increased. The government has been running a budget deficit since 1988. The disappearance of a revenue surplus has made Brunei's economy more vulnerable to petroleum price fluctuations.