Year	Number of
1990	213.5
1991	216.56
1992	220.12
1993	223.23
1994	224.79
1995	226.2
1996	226.19
1997	226.12
1998	225.8
1999	225
2000	223.82
2001	223.83
2002	223.8
2003	223.13
2004	222.82
2005	222.68
2006	225.86
2007	229.84
2008	233.95
2009	238.56
2010	243.73
2011	247.42
2012	251.84
2013	256.94
2014	262.86
2015	270.11
2016	277.94