Year	Number of
1990	395.01
1991	402.61
1992	412.39
1993	422.76
1994	434.89
1995	446.43
1996	461.23
1997	473.51
1998	486.42
1999	496.26
2000	507.82
2001	506.66
2002	506.63
2003	506.45
2004	506.29
2005	507.66
2006	511.46
2007	514.79
2008	518.43
2009	524.31
2010	528.79
2011	530.93
2012	531.77
2013	533.24
2014	538
2015	540.48
2016	544.18