Year	Number of
1990	210.26
1991	214.77
1992	216.42
1993	218.34
1994	222.29
1995	224.44
1996	222.25
1997	223
1998	227.16
1999	231.3
2000	230.41
2001	226.16
2002	218.78
2003	219.56
2004	222.24
2005	226.01
2006	223.4
2007	217.2
2008	221.36
2009	223.83
2010	221.05
2011	222.7
2012	224.07
2013	224.11
2014	227.36
2015	233.07
2016	239.01