Year	Number of
1990	59.47
1991	60.87
1992	62.46
1993	64.16
1994	65.92
1995	67.83
1996	68.69
1997	69.71
1998	70.81
1999	71.97
2000	73.29
2001	73.86
2002	74.51
2003	75.25
2004	76.08
2005	77.13
2006	78.09
2007	79.03
2008	80.19
2009	81.51
2010	83.12
2011	84.32
2012	85.87
2013	87.54
2014	89.36
2015	91.34
2016	93.54