Year	Number
1996	0.409431099891663
1998	0.345668405294418
2000	0.342506408691406
2002	0.316015273332596
2003	0.301584661006927
2004	0.315975606441498
2005	0.30609455704689
2006	0.273782998323441
2007	0.262691110372543
2008	0.263591170310974
2009	0.272184789180756
2010	0.260473906993866
2011	0.25491926074028
2012	0.22986213862896
2013	0.236392676830292
2014	0.200713470578194
2015	0.205684825778008
2016	0.206087306141853
2017	0.213935792446136
2018	0.212307974696159
2019	0.229520440101624
2020	0.232469826936722
2021	0.234690770506859
2022	0.233039766550064