Year	Number
1996	2.11024570465088
1998	2.14845299720764
2000	2.18196034431458
2002	2.2625732421875
2003	2.28462529182434
2004	2.35213804244995
2005	2.19131422042847
2006	2.32255101203918
2007	2.31768393516541
2008	2.29752516746521
2009	2.3803186416626
2010	2.32940340042114
2011	2.29086756706238
2012	2.30788779258728
2013	2.33409142494202
2014	2.24964022636414
2015	2.23334360122681
2016	2.23653864860535
2017	2.19515657424927
2018	2.1350314617157
2019	2.13102984428406
2020	2.11714220046997
2021	2.17015552520752
2022	2.16333413124084