Year	Number of
1990	35.39
1991	36.07
1992	36.89
1993	37.86
1994	39.03
1995	41.05
1996	42.87
1997	45
1998	47.47
1999	50.38
2000	54.31
2001	58.5
2002	63.55
2003	69.38
2004	75.88
2005	83.1
2006	92.11
2007	101.8
2008	112.99
2009	126.84
2010	144.72
2011	158.65
2012	176.23
2013	196.88
2014	219.72
2015	244.14
2016	270.74