Year	Number of
1990	220.74
1991	210.15
1992	213.25
1993	216.9
1994	217.7
1995	225.45
1996	222.06
1997	226.47
1998	232.76
1999	244.19
2000	255.54
2001	274.46
2002	285.26
2003	306.22
2004	322.42
2005	344.84
2006	367.01
2007	387.04
2008	405.29
2009	429.43
2010	455.35
2011	479.69
2012	503.53
2013	528.37
2014	552.98
2015	578.14
2016	604.1