Year	Number of
1990	80.27
1991	82.95
1992	85.8
1993	88.87
1994	92.12
1995	95.66
1996	98.01
1997	100.62
1998	103.79
1999	106.95
2000	110.15
2001	113.19
2002	116.33
2003	120.03
2004	123.82
2005	127.81
2006	130.9
2007	133.97
2008	137.39
2009	141.19
2010	145.52
2011	148.5
2012	152.02
2013	155.58
2014	159.51
2015	163.8
2016	168.47