Year	Number
1996	0.480888694524765
1998	0.453148931264877
2000	0.461006760597229
2002	0.427986711263657
2003	0.395839601755142
2004	0.365187674760818
2005	0.287387371063232
2006	0.315462857484818
2007	0.32002717256546
2008	0.336053848266602
2009	0.350421518087387
2010	0.336508005857468
2011	0.339280128479004
2012	0.326958298683167
2013	0.329349517822266
2014	0.341326415538788
2015	0.23686172068119
2016	0.233970940113068
2017	0.234347388148308
2018	0.226347967982292
2019	0.228423789143562
2020	0.226407334208488
2021	0.240289986133575
2022	0.246608749032021