Year	Number
1995	2.3935572579
1996	2.2573561186
1997	2.1211549794
1998	1.9849538401
1999	1.8487527008
2000	1.7125515616
2001	1.5763504223
2002	1.4407778433
2003	1.3961107837
2004	1.3514437242
2005	1.3067766647
2006	1.2621096052
2007	1.2174425457
2008	1.3482616382
2009	2.3270477313
2010	1.621685327
2011	2.1750147319
2012	1.4625810253
2013	1.390689452
2014	0.9929286977
2015	1.0412492634
2016	1.0952143017
2017	1.0672808544
2018	1.0804301709
2019	1.0526163819
2020	1.0678314673