Year	Number
2005	2.277053455
2006	2.5723598435
2007	2.8676662321
2008	3.1629726206
2009	3.4582790091
2010	3.7535853977
2011	4.0488917862
2012	4.3441981747
2013	4.6395045632
2014	4.9348109518
2015	5.1173402868
2016	4.9934810952
2017	4.7718383312
2018	4.7718383312
2019	4.7913950456
2020	4.7913950456