Year	Number of
1990	167.42
1991	168.49
1992	169.42
1993	171.13
1994	173.02
1995	177.01
1996	176.4
1997	173.68
1998	171.49
1999	165.04
2000	163.77
2001	154.78
2002	151.75
2003	150.53
2004	151.76
2005	154.05
2006	153.28
2007	153.86
2008	154.52
2009	155.69
2010	160.14
2011	163.39
2012	167.3
2013	171.06
2014	175.23
2015	180.32
2016	185.9