Year	per person
1971	3.19
1972	2.828
1973	2.704
1974	2.702
1975	2.699
1976	2.78
1977	2.831
1978	3.153
1979	3.534
1980	4.191
1981	4.238
1982	4.461
1983	4.618
1984	4.892
1985	5.308
1986	5.209
1987	4.652
1988	5.74
1989	5.626
1990	6.412
1991	7.261
1992	7.777
1993	8.178
1994	8.754
1995	9.361
1996	9.576
1997	9.507
1998	8.4
1999	7.883
2000	8.04
2001	5.958
2002	8.7
2003	9.251
2004	9.969
2005	10.53
2006	13.07
2007	14.6
2008	15.06