Year	Number of
1990	55.63
1991	59.63
1992	65.61
1993	69.28
1994	71.71
1995	69.05
1996	71.11
1997	69.02
1998	67.9
1999	69.81
2000	71.79
2001	73.71
2002	75.82
2003	77.5
2004	77.95
2005	80.43
2006	80.8
2007	83.16
2008	83.54
2009	83.17
2010	85.9
2011	87.58
2012	88.32
2013	90.49
2014	91.57
2015	92.44
2016	94.83