Year	Number of
1990	148.09
1991	156.87
1992	162.16
1993	177.9
1994	188.64
1995	203.76
1996	217.27
1997	223.95
1998	231.41
1999	240.27
2000	249.46
2001	258.76
2002	268.04
2003	282.09
2004	300.98
2005	320.68
2006	331.8
2007	336.79
2008	343.45
2009	350.64
2010	361.77
2011	376.38
2012	393.3
2013	413.11
2014	434.41
2015	456.52
2016	473.81