Year	Number of
1990	248.38
1991	256.24
1992	265.22
1993	275.4
1994	286.38
1995	298.16
1996	309.48
1997	321.6
1998	334.34
1999	348.2
2000	363.33
2001	372.64
2002	382.93
2003	393.55
2004	404.78
2005	416.62
2006	419.83
2007	422.81
2008	426.79
2009	431.9
2010	438.54
2011	451.22
2012	466.14
2013	482.84
2014	500.53
2015	518.82
2016	537.54