Year	Number of
1990	173.54
1991	169.95
1992	174.94
1993	172.93
1994	179.18
1995	176.19
1996	191.6
1997	205.65
1998	197.68
1999	221.61
2000	235.7
2001	248.08
2002	267.17
2003	276.6
2004	298.78
2005	313.01
2006	334.19
2007	349.28
2008	366.29
2009	394.86
2010	412.89
2011	431.9
2012	452.6
2013	463.05
2014	466.32
2015	453.01
2016	446.38