Year	Number of
1990	308.09
1991	313.02
1992	319.92
1993	333.14
1994	347.18
1995	358.41
1996	365.32
1997	369.91
1998	378.44
1999	388.19
2000	398.88
2001	407.37
2002	415.64
2003	422.41
2004	429.25
2005	432.7
2006	431.28
2007	431.19
2008	433.68
2009	439.33
2010	448.78
2011	451.67
2012	455.35
2013	459.51
2014	465.21
2015	472.39
2016	479.86