Year	Number of
1990	54.78
1991	55.56
1992	56.64
1993	57.85
1994	58.97
1995	59.89
1996	62.95
1997	66.32
1998	70.26
1999	74.68
2000	79.84
2001	82.74
2002	85.69
2003	88.4
2004	91.24
2005	94.24
2006	98.39
2007	102.78
2008	107.34
2009	111.97
2010	116.66
2011	119.1
2012	121.32
2013	123.37
2014	125.5
2015	127.8
2016	129.68