Year	per 1000 people
1960	0.267
1965	0.311
1970	0.509
1975	0.49
1981	0.523
1984	0.697
1990	0.45
1993	0.426
1995	0.34
1997	1.299
2001	1.216
2007	0.336
2010	0.444
2011	0.473