Year	Number of
1990	84.47
1991	90.34
1992	95.13
1993	99.73
1994	103.31
1995	106.74
1996	110.91
1997	117.1
1998	121.5
1999	124.07
2000	127.6
2001	130.98
2002	134.19
2003	137.19
2004	138.08
2005	138.78
2006	138.92
2007	137.75
2008	138.28
2009	139.74
2010	140.72
2011	141.19
2012	143.28
2013	145.8
2014	147.52
2015	150.44
2016	153.66