Year	per person
1800	1.807
1820	1.845
1913	4.113
1950	8.059
1973	23.55
1990	27.83
1991	26.38
1992	22.54
1993	20.58
1994	17.96
1995	17.22
1996	16.62
1997	16.88
1998	16.01
1999	17.09
2000	18.88
2001	19.94
2002	20.98
2003	22.62
2004	24.35
2005	26.01
2006	28.14
2007	30.54
2008	32.3
2009	29.88