Year	Number of
1990	82.68
1991	84.84
1992	84.97
1993	85.05
1994	86.11
1995	87.48
1996	91.03
1997	95.01
1998	99.97
1999	106.34
2000	113.5
2001	122.01
2002	131.1
2003	140.06
2004	148.94
2005	157.94
2006	167.39
2007	176.53
2008	185.35
2009	193.42
2010	202.23
2011	212.01
2012	222.44
2013	232.63
2014	243.25
2015	255.28
2016	269.15