Year	per 1,000 people
1970	1.5321532995846068
1975	1.6071557595198436
1980	2.2738571830412706
1981	2.219532312305703
1985	2.867997422061629
1987	3.066006145558054
1990	3.494422834140737
1991	2.801535125135981
2000	2.183405045825556
2001	2.0578839154864155
2002	1.984804447592312
2003	2.157124239507087
2005	2.076191312231798
2006	2.0420493680330263
2007	2.0125237323079754
2008	2.0516548439213107
2009	2.010337774011141
2010	2.082467299300156
2011	2.162590469736728
2012	2.23698645043859
2013	2.339365624464534
2014	2.3520958381973034
2015	2.3466912150951678
2016	2.3866348305429517
2017	2.491199182621781