Year	Number of
1990	46.72
1991	47.98
1992	49.4
1993	50.82
1994	52.34
1995	54.26
1996	55.29
1997	56.32
1998	57.21
1999	56.33
2000	55.46
2001	53.79
2002	53.31
2003	52.72
2004	53.12
2005	52.62
2006	53.26
2007	54.1
2008	54.6
2009	55.71
2010	56.45
2011	56.67
2012	57.88
2013	59.18
2014	60.4
2015	61.82
2016	63.12