Year	Total
1971	1677000000
1972	1961000000
1973	2182000000
1974	2174000000
1975	2336000000
1976	2510000000
1977	2653000000
1978	2845000000
1979	2912000000
1980	2986000000
1981	2899000000
1982	3216000000
1983	3472000000
1984	3323000000
1985	3496000000
1986	3601000000
1987	4008000000
1988	4840000000
1989	5173000000
1990	5318000000
1991	5612000000
1992	6885000000
1993	7026000000
1994	7698000000
1995	8119000000
1996	8641000000
1997	9478000000
1998	10150000000
1999	10190000000
2000	11570000000
2001	11810000000
2002	12730000000
2003	13220000000
2004	13520000000
2005	13720000000
2006	14320000000
2007	15050000000
2008	15230000000