Year	Number of
1990	41
1991	43.61
1992	46.39
1993	49.37
1994	52.6
1995	56.12
1996	59.37
1997	62.86
1998	66.67
1999	70.67
2000	74.85
2001	78.51
2002	82.4
2003	86.78
2004	91.47
2005	96.55
2006	101.09
2007	105.88
2008	111.15
2009	116.75
2010	122.75
2011	128.69
2012	135.08
2013	141.92
2014	149.28
2015	157.2
2016	165.49