Year	Number of
1990	344.15
1991	341.14
1992	327.49
1993	315.6
1994	311.26
1995	304.58
1996	303.38
1997	303.73
1998	306.41
1999	311.29
2000	318.66
2001	326.93
2002	337.39
2003	348.36
2004	360.28
2005	372.15
2006	381.6
2007	390.98
2008	400.96
2009	409.39
2010	418.41
2011	425.9
2012	434.62
2013	443.34
2014	452.29
2015	462.59
2016	473.77