Year	Number of
1990	58.86
1991	59.9
1992	60.12
1993	63.73
1994	65.17
1995	66.29
1996	68.02
1997	68.72
1998	70.16
1999	70.74
2000	70.71
2001	70.73
2002	71.54
2003	72.15
2004	72.89
2005	74.05
2006	75.29
2007	76.02
2008	76.85
2009	78.07
2010	80.64
2011	81.75
2012	82.23
2013	83.69
2014	84.81
2015	86.32
2016	87.87