Year	Number of
1990	56.89
1991	56.64
1992	57.12
1993	57.2
1994	57.88
1995	58.25
1996	58.65
1997	57.41
1998	57.3
1999	58.71
2000	60.41
2001	62.44
2002	63.26
2003	64.42
2004	66.64
2005	67.74
2006	68.63
2007	69.64
2008	71.44
2009	73.46
2010	75.3
2011	77.05
2012	79.23
2013	81.42
2014	83.31
2015	85.5
2016	88.11