Year	Number of
1990	122.91
1991	124.14
1992	126.73
1993	130.43
1994	131.97
1995	133.9
1996	133.13
1997	132.85
1998	133.39
1999	135.09
2000	136.65
2001	142.43
2002	148.43
2003	154.35
2004	160.9
2005	162.88
2006	164.82
2007	167.11
2008	169.73
2009	172.27
2010	174.56
2011	176.21
2012	177.86
2013	179.71
2014	181.85
2015	184.21
2016	185.97