Year	Number of
1990	80.06
1991	80.18
1992	80.89
1993	83.14
1994	86.43
1995	88.86
1996	92.44
1997	95.77
1998	100.68
1999	105.36
2000	109.35
2001	112.2
2002	114.64
2003	119.15
2004	124.7
2005	131.2
2006	137.7
2007	144.69
2008	151.93
2009	158.28
2010	164.91
2011	165.79
2012	167.43
2013	168.32
2014	166.89
2015	165.94
2016	164.71