Year	Number
2004	0.42519822716713
2005	0.369224309921265
2006	0.362917214632034
2007	0.331106036901474
2008	0.332146733999252
2009	0.311091840267181
2010	0.301820993423462
2011	0.294137328863144
2012	0.267991930246353
2013	0.279365241527557
2014	0.235650628805161
2015	0.238645374774933
2016	0.242126181721687
2017	0.252123653888702
2018	0.247710168361664
2019	0.266850560903549
2020	0.266803950071335
2021	0.273823916912079
2022	0.269579499959946