Year	Number of
1990	56.15
1991	58.09
1992	60.09
1993	62.04
1994	64.18
1995	66.52
1996	70.35
1997	74.41
1998	78.84
1999	83.63
2000	88.85
2001	94.17
2002	100.02
2003	106.78
2004	114.03
2005	121.73
2006	126.37
2007	130.98
2008	135.64
2009	140.75
2010	146.58
2011	147.69
2012	149.46
2013	151.44
2014	153.68
2015	156.05
2016	158.52