Year	Number
2008	2.5260804769
2009	2.9698353539
2010	3.4126587854
2011	3.8554822168
2012	4.2983056482
2013	4.7411290797
2014	5.1839525111
2015	5.6267759425
2016	6.069599374
2017	6.5124228054
2018	6.9552462368
2019	7.1814456036
2020	7.1814456036