Year	Number of
1990	463.69
1991	452.18
1992	460.11
1993	461.66
1994	469.14
1995	462.71
1996	457.37
1997	458.02
1998	463.05
1999	467.99
2000	470.19
2001	469.46
2002	477.9
2003	500.64
2004	506
2005	506.93
2006	500.88
2007	501.1
2008	527.62
2009	535.17
2010	539.46
2011	524.21
2012	547.96
2013	515.42
2014	513.66
2015	520.59
2016	523.4