Year	Number of
1990	167.27
1991	169.54
1992	170.14
1993	169.18
1994	168.72
1995	169.81
1996	172.46
1997	176.72
1998	182.61
1999	189.21
2000	196.22
2001	199.75
2002	204.15
2003	210.14
2004	215.91
2005	221.3
2006	226.79
2007	231.21
2008	235.96
2009	241.11
2010	247.2
2011	250.75
2012	255.29
2013	260.05
2014	264.87
2015	269.53
2016	274.53