Year	Number of
1990	235.5
1991	248.91
1992	263.07
1993	278.83
1994	298.48
1995	311.11
1996	315.75
1997	317.1
1998	324.22
1999	328.06
2000	327.63
2001	333.43
2002	339.35
2003	338
2004	341.28
2005	344.31
2006	356.86
2007	366.71
2008	376.77
2009	391.33
2010	406.33
2011	421.11
2012	435.57
2013	452.27
2014	468.6
2015	487.06
2016	502.26