Year	Number of
1990	39.11
1991	41.15
1992	43.86
1993	46.6
1994	49.17
1995	51.6
1996	53.8
1997	55.33
1998	58.38
1999	61.59
2000	64.45
2001	67.59
2002	71.55
2003	75.51
2004	78.98
2005	82.36
2006	86.62
2007	90.32
2008	94.74
2009	100.14
2010	105.71
2011	110.38
2012	115.16
2013	119.04
2014	123.04
2015	126.63
2016	129.74