Year	Number of
1990	203.5
1991	204.19
1992	208.1
1993	208.94
1994	211.15
1995	218.8
1996	222.74
1997	226.84
1998	231.69
1999	236.17
2000	240.16
2001	243.48
2002	247.23
2003	251.89
2004	256.5
2005	260.99
2006	264.12
2007	267.16
2008	271.06
2009	275.97
2010	281.27
2011	286.21
2012	291.66
2013	297.66
2014	304.13
2015	311.04
2016	318.05