Year	Number of
1990	49.18
1991	51.21
1992	53.39
1993	55.84
1994	58.38
1995	61.03
1996	63.98
1997	67.06
1998	70.45
1999	73.95
2000	77.62
2001	81.41
2002	85.4
2003	89.74
2004	94.32
2005	99.2
2006	103.8
2007	108.6
2008	113.81
2009	119.33
2010	125.26
2011	129.56
2012	134.21
2013	139.21
2014	144.49
2015	150.05
2016	156.08