Year	Number of
1990	72.94
1991	75.45
1992	80.19
1993	84.11
1994	91.83
1995	97.62
1996	102.49
1997	107.59
1998	115
1999	119.88
2000	122.09
2001	123.16
2002	125.13
2003	127.73
2004	131.45
2005	133.3
2006	136.07
2007	138.78
2008	141.57
2009	142.97
2010	144.46
2011	144.91
2012	145.11
2013	145.49
2014	147.64
2015	150.29
2016	153.62