Year	per 100,000 population
2000	4.3
2001	4.3
2002	4.3
2003	4
2004	4.1
2005	4
2006	4
2007	4
2008	4
2009	4
2010	3.9
2011	3.8
2012	3.6
2013	3.6
2014	3.4
2015	3.3
2016	3.3
2017	3.1
2018	3.2
2019	3.3