Year	Number of
1990	324.64
1991	321.46
1992	318.21
1993	314.08
1994	316.59
1995	320.8
1996	325.31
1997	340.62
1998	345.96
1999	360.05
2000	372.9
2001	395.22
2002	427.21
2003	451.75
2004	478.02
2005	500.69
2006	516.72
2007	536.95
2008	549.1
2009	561.85
2010	574.4
2011	582.26
2012	588.11
2013	592.73
2014	599.9
2015	613.36
2016	626.89