Year	per 1,000
1990	9.300786201925378
1991	9.230681112936416
1992	8.604143036204555
1993	8.264288423970541
1994	7.977531421530311
1995	7.674363814029324
1996	7.39194784694502
1997	7.16835350719038
1998	6.954368858879187
1999	6.7114565153461525
2000	6.521966859809972
2001	6.3111491087819225
2002	6.138423781640826
2003	5.9934432906509
2004	6.031703958921826
2005	5.730650586674151
2006	5.42566327079234
2007	5.249199529891584
2008	5.3294450588934685
2009	4.865694196078323
2010	4.743512184078885
2011	4.451402929536548
2012	4.267409935699092
2013	4.096979063884292
2014	3.9070438681781816
2015	3.739886128025362
2016	3.5791086990628624
2017	3.443406271497128
2018	3.3007213278478336
2019	3.1754207163505193
2020	3.0723277569702923
2021	2.9676580153262475
2022	2.8600038655330473