Surging crude oil prices led to the Excess Crude Account increasing almost four-fold, from $5.1 billion in 2005 to over $20 billion by November 2008, accounting for more than one-third of Nigeria's external reserves at that time. By June 2010, the account had fallen to less than $4 billion due to budget deficits at all levels of government in Nigeria and the steep drop in oil prices. In 2010, Nigeria's National Economic Council approved a plan to replace the Excess Crude Account with a national sovereign wealth fund.