The number of country A forces in country B decreased to approximately 34,000 in 2014 from a high of about 100,000 in 2008. The amount of country A funding for country B security forces also decreased during this period. The function f (x) = -1.330x + 5.149x +5.517 can be used to estimate the amount of country A funding for country B security forces, in billions of dollars, x years after January 2007. In what year was the amount of country A funding for country B security forces about $ 10.5 billion?