Year	Number of
1990	262.96
1991	266.16
1992	265.9
1993	267.48
1994	268.31
1995	269.11
1996	270.19
1997	271.89
1998	275.77
1999	283.56
2000	285.06
2001	288.39
2002	292.81
2003	300.09
2004	311.36
2005	314.79
2006	326.4
2007	336.68
2008	344.17
2009	352.9
2010	363.91
2011	377.74
2012	397.52
2013	413.54
2014	425.26
2015	438.72
2016	454.33