Year	Number of
1990	451.76
1991	421.59
1992	381.95
1993	360.06
1994	349.67
1995	363.5
1996	361.05
1997	366.6
1998	373.15
1999	378.93
2000	399.67
2001	413.69
2002	435.92
2003	438.03
2004	439.86
2005	457.04
2006	469.41
2007	480.16
2008	489.3
2009	494.19
2010	500.78
2011	497
2012	494.63
2013	496.41
2014	499.32
2015	506.72
2016	516.58