Year	Number of
1990	304.12
1991	308.38
1992	314.87
1993	324.17
1994	325.37
1995	328.82
1996	332.47
1997	339.37
1998	344.88
1999	355.4
2000	373.36
2001	383.95
2002	394.42
2003	407.32
2004	422.08
2005	438.13
2006	448.18
2007	462.4
2008	470.86
2009	477.81
2010	487.72
2011	498.69
2012	508.46
2013	518.66
2014	528.71
2015	538.7
2016	550.42