Year	Number of
1990	262.18
1991	265.51
1992	262.87
1993	258.59
1994	255.9
1995	256.65
1996	261.97
1997	270.87
1998	281.92
1999	293.29
2000	304.26
2001	312.39
2002	321.83
2003	333.17
2004	344.18
2005	355.05
2006	369.56
2007	383.53
2008	397.93
2009	412.52
2010	427.93
2011	431.81
2012	440.4
2013	449.06
2014	458.2
2015	461.21
2016	464.73