Year	Number of
1990	295.02
1991	279.3
1992	270.42
1993	266.25
1994	261.91
1995	269.46
1996	269.33
1997	270.15
1998	296.97
1999	326.81
2000	357.55
2001	387.03
2002	427.26
2003	450.69
2004	492.13
2005	481.75
2006	479.84
2007	470.62
2008	481.2
2009	498.41
2010	491.74
2011	480.46
2012	473.07
2013	467.76
2014	490.99
2015	494.2
2016	501.53