Year	Number of
1990	70.22
1991	74.19
1992	78.29
1993	82.69
1994	87.72
1995	93.54
1996	100.23
1997	107.38
1998	115.34
1999	123.86
2000	133.31
2001	137.6
2002	142.64
2003	148.25
2004	154.48
2005	161.43
2006	165.9
2007	170.59
2008	175.99
2009	182.01
2010	188.71
2011	199.74
2012	211.62
2013	224.95
2014	238.5
2015	252.21
2016	267.42