Year	Number of
1990	63.49
1991	64.9
1992	66.42
1993	68.05
1994	69.8
1995	71.69
1996	71.57
1997	71.55
1998	71.57
1999	71.62
2000	71.72
2001	71.04
2002	70.4
2003	69.87
2004	69.5
2005	69.32
2006	70.73
2007	72.31
2008	74.15
2009	76.09
2010	78.09
2011	81.47
2012	84.98
2013	88.61
2014	92.48
2015	96.66
2016	101.27