Year	Number of
1990	163.94
1991	172.26
1992	179.54
1993	186.79
1994	194.62
1995	203.85
1996	214.32
1997	226.93
1998	240.74
1999	256.19
2000	273.1
2001	293.79
2002	316.46
2003	341.19
2004	368.48
2005	398.69
2006	410.19
2007	422.28
2008	436.09
2009	450.65
2010	465.98
2011	480.72
2012	496.65
2013	513.6
2014	531.35
2015	549.77
2016	568.9