Year	Number of
1990	590.44
1991	572.76
1992	562.01
1993	549.88
1994	532.4
1995	517.99
1996	498.3
1997	481.17
1998	461.25
1999	448.61
2000	435.71
2001	426.65
2002	421.19
2003	412.83
2004	401.52
2005	397.87
2006	401.92
2007	401.04
2008	395.29
2009	394.73
2010	397.38
2011	399.4
2012	406.39
2013	407.35
2014	404.46
2015	412.03
2016	422.44