Year	per 1000 people
1960	0.222
1970	0.346
1984	0.49
1988	0.553
1990	0.5
1993	0.578
1995	0.65
1997	0.405
1999	0.582
2000	0.571
2001	0.569
2002	0.568
2003	0.567
2006	0.668