Year	Number of
1990	57.08
1991	57.9
1992	58.96
1993	59.32
1994	59.33
1995	59.37
1996	60.03
1997	61.03
1998	62.13
1999	63.15
2000	63.89
2001	65.83
2002	68.05
2003	70.49
2004	72.85
2005	75.19
2006	76.25
2007	77.35
2008	78.36
2009	79.34
2010	80.35
2011	81.13
2012	82.18
2013	83.4
2014	84.8
2015	86.29
2016	87.89