Year	Number of
1990	280.37
1991	272.62
1992	271.95
1993	268.6
1994	274.52
1995	280.61
1996	291.74
1997	304.83
1998	306.71
1999	304.18
2000	305.2
2001	311.17
2002	320.46
2003	329.97
2004	347.27
2005	359.24
2006	377.85
2007	388.5
2008	404.96
2009	443.81
2010	454.92
2011	477.72
2012	466.07
2013	467.49
2014	465.66
2015	467.79
2016	494.43