Year	Number of
1990	58.9
1991	59.94
1992	61.22
1993	62.64
1994	64.18
1995	65.86
1996	66.71
1997	67.61
1998	68.51
1999	69.43
2000	70.46
2001	70.82
2002	71.3
2003	71.86
2004	72.49
2005	73.32
2006	74.17
2007	75.08
2008	76.24
2009	77.52
2010	78.98
2011	80.04
2012	81.25
2013	82.49
2014	83.88
2015	85.44
2016	87.12