Year	Number of
1990	149.64
1991	154.18
1992	157.97
1993	163.22
1994	165.39
1995	171.87
1996	173.76
1997	178.09
1998	182.55
1999	189.14
2000	195.97
2001	201.11
2002	206.22
2003	213.34
2004	219.48
2005	226.93
2006	235.14
2007	242.92
2008	251.99
2009	261.45
2010	271.5
2011	281.42
2012	291.68
2013	302.25
2014	313
2015	324.43
2016	337.3