Year	Number of
1990	152.45
1991	153.13
1992	153.74
1993	154.11
1994	155.45
1995	157.54
1996	160.61
1997	164.74
1998	169.98
1999	174.23
2000	177.76
2001	180.52
2002	184.88
2003	189.21
2004	193.07
2005	197.18
2006	201.21
2007	205.43
2008	209.62
2009	213.24
2010	217.78
2011	221.57
2012	228.19
2013	232.57
2014	237.95
2015	243.44
2016	250.45