Year	per 1,000 people
1960	1.22574877738953
1970	1.15489995479584
1980	1.46490001678467
1981	1.13119995594025
1985	0.359600007534027
1990	0.8338999748
1991	0.5005000234
1992	0.2231000066
1993	0.2390999943
1994	0.2336000055
2005	0.5
2010	0.5