Year	per 1000 people
1960	1.064
1965	1.136
1970	1.093
1975	1.111
1981	1.997
1984	1.926
1985	1.947
1990	3.68
1992	3.226
1995	3.56
1996	3.703
1999	3.745
2002	3.721
2007	4.181
2008	3.938
2010	3.736