Year	Number of
1990	44.39
1991	44.9
1992	45.53
1993	46.35
1994	47.46
1995	49.5
1996	50.05
1997	52.24
1998	53.81
1999	56.82
2000	59.68
2001	60.05
2002	59.86
2003	62.31
2004	62.57
2005	62.09
2006	62.44
2007	60.49
2008	59.08
2009	60.86
2010	58.75
2011	57.99
2012	58.7
2013	59.38
2014	60.54
2015	61.71
2016	62.42