Year	Number of
1990	146.17
1991	150.41
1992	153.75
1993	155.78
1994	160.19
1995	164.21
1996	167.94
1997	170.56
1998	172.82
1999	173.25
2000	174
2001	173.94
2002	173.97
2003	174.54
2004	175.15
2005	175.8
2006	175.9
2007	175.8
2008	175.67
2009	176.01
2010	177.56
2011	179.08
2012	180.6
2013	184.32
2014	188.07
2015	191.79
2016	196.65