Year	Number of
1990	109.87
1991	112.64
1992	115.43
1993	123.41
1994	128.26
1995	136.56
1996	139.02
1997	139.36
1998	142.77
1999	148.22
2000	153.59
2001	159.17
2002	159.5
2003	162.43
2004	162.07
2005	166
2006	169.86
2007	170.87
2008	172.16
2009	173.21
2010	176.71
2011	180.64
2012	184.9
2013	187.33
2014	189.47
2015	191.07
2016	193.88