Year	Number of
1990	81.53
1991	81.84
1992	82.01
1993	81.28
1994	80.96
1995	81.01
1996	81.19
1997	82.24
1998	84.78
1999	89.44
2000	97.19
2001	107.97
2002	121.75
2003	137.48
2004	152.21
2005	165.18
2006	176.41
2007	185.46
2008	192.6
2009	198.23
2010	204.03
2011	210.01
2012	209.19
2013	210.49
2014	213.69
2015	214.56
2016	214.32