Year	Number of
1990	226.3
1991	235.54
1992	245.6
1993	256.51
1994	268.38
1995	281.51
1996	289.06
1997	297.23
1998	305.95
1999	315.05
2000	324.59
2001	335.74
2002	347.49
2003	360.38
2004	373.86
2005	388.2
2006	389.75
2007	391.42
2008	393.78
2009	397.14
2010	401.82
2011	415.69
2012	431.65
2013	448.87
2014	467.14
2015	486.28
2016	506.05