Year	Number
1996	2.9
1997	3.08
1998	4.1
1999	2.7
2000	1.7
2001	5.19
2002	5.13
2003	3.66
2004	3.03
2005	7.37
2006	6.12
2007	11.14
2008	6.05
2009	9.83
2010	9.2
2011	10.78
2012	8.01
2013	18.89
2014	15.89
2015	12.15
2016	13.91
2017	20.78
2018	20.64
2019	19.68
2020	22.73