Year	Number
1996	0.421715974807739
1998	0.381433337926865
2000	0.396205484867096
2002	0.392881572246552
2003	0.330509543418884
2004	0.316001296043396
2005	0.300349622964859
2006	0.308776706457138
2007	0.284595400094986
2008	0.282790422439575
2009	0.246055126190186
2010	0.243547096848488
2011	0.244249582290649
2012	0.221984326839447
2013	0.228019788861275
2014	0.196386188268661
2015	0.196433380246162
2016	0.203295975923538
2017	0.209813088178635
2018	0.208318024873734
2019	0.223971575498581
2020	0.226481333374977
2021	0.22979348897934
2022	0.226615026593208