Year	Number of
1990	179.42
1991	185.6
1992	193.13
1993	201.03
1994	210.04
1995	218.55
1996	226.24
1997	234.49
1998	243.87
1999	248.71
2000	253.63
2001	256.67
2002	261.49
2003	270.97
2004	278.84
2005	288.83
2006	303.92
2007	319.39
2008	335.79
2009	352.14
2010	367.17
2011	386.31
2012	406.94
2013	433.34
2014	459.55
2015	488.17
2016	517.22