Year	Number of
1990	193.42
1991	197.09
1992	207.04
1993	219.7
1994	229.59
1995	240.25
1996	241.15
1997	240.81
1998	248.55
1999	255.57
2000	273.53
2001	282.64
2002	295.48
2003	313.39
2004	329.39
2005	340.86
2006	357.26
2007	376.27
2008	395.43
2009	413.23
2010	438.85
2011	455.84
2012	465.75
2013	473.13
2014	488.59
2015	492.66
2016	501.43