Year	Number of
1990	44.02
1991	45.65
1992	47.36
1993	49.15
1994	51.06
1995	53.22
1996	55.06
1997	57.13
1998	59.35
1999	61.66
2000	64.14
2001	66.21
2002	68.47
2003	70.86
2004	73.39
2005	76.17
2006	78.53
2007	80.85
2008	83.42
2009	86.1
2010	89.05
2011	91.32
2012	93.83
2013	96.43
2014	99.17
2015	102.07
2016	105.31