Year	Number of
1990	310.96
1991	318.22
1992	329.74
1993	326.35
1994	335.7
1995	328.57
1996	325.59
1997	320.62
1998	319.62
1999	318.77
2000	312.36
2001	322.15
2002	341.3
2003	345.72
2004	345.37
2005	350.2
2006	360.55
2007	368.21
2008	386.86
2009	403.89
2010	413.2
2011	425.7
2012	442.56
2013	458.34
2014	483.41
2015	506
2016	527.99