Year	Total
1971	3235000000
1972	3625000000
1973	3925000000
1974	4229000000
1975	4611000000
1976	5037000000
1977	5332000000
1978	5876000000
1979	5884000000
1980	6175000000
1981	6367000000
1982	6639000000
1983	7001000000
1984	7518000000
1985	8007000000
1986	8312000000
1987	8732000000
1988	8873000000
1989	9237000000
1990	9625000000
1991	9875000000
1992	10340000000
1993	11400000000
1994	13190000000
1995	14850000000
1996	16010000000
1997	15510000000
1998	14510000000
1999	14050000000
2000	13820000000
2001	14240000000
2002	14120000000
2003	14510000000
2004	14530000000
2005	14720000000
2006	15200000000
2007	14650000000
2008	14710000000