Year	Number of
1990	302.87
1991	307.33
1992	311.79
1993	316.31
1994	321.14
1995	326.66
1996	332.37
1997	338.69
1998	345.4
1999	352.64
2000	360.67
2001	369.12
2002	378.35
2003	388.26
2004	398.84
2005	410.37
2006	420.37
2007	430.52
2008	442.39
2009	454.86
2010	468.41
2011	480.59
2012	493.48
2013	507.55
2014	522.07
2015	537
2016	553.03