Year	Number of
1990	281.3
1991	274.26
1992	270.41
1993	259.18
1994	254.91
1995	242.42
1996	236.46
1997	232.5
1998	230.87
1999	232.97
2000	234.66
2001	237.49
2002	239.52
2003	239.86
2004	239.69
2005	238.87
2006	234.31
2007	235.48
2008	240.81
2009	234.05
2010	228.41
2011	224.29
2012	222.25
2013	221.19
2014	224.41
2015	229.27
2016	236.28