Year	Number of
1990	336.39
1991	334.59
1992	334.21
1993	333.43
1994	337.61
1995	341.41
1996	342.9
1997	346.16
1998	353.22
1999	360.89
2000	372.27
2001	374.64
2002	381.41
2003	393.35
2004	391.05
2005	398.28
2006	401.36
2007	408.62
2008	421.49
2009	431.04
2010	436.42
2011	447.96
2012	462.16
2013	477.29
2014	491.83
2015	506.18
2016	523.35