Year	Number of
1990	209.82
1991	210.67
1992	211.86
1993	210.17
1994	209.26
1995	208
1996	201.13
1997	195.9
1998	194.08
1999	189.35
2000	188.93
2001	192.37
2002	199.73
2003	209.28
2004	215.44
2005	220.24
2006	223.86
2007	226.05
2008	226.09
2009	224.75
2010	225.07
2011	226.12
2012	225.84
2013	227.57
2014	233.22
2015	227.87
2016	221.27