Year	Number of
1990	105.09
1991	104.24
1992	103.09
1993	101.3
1994	104.88
1995	108.33
1996	118.58
1997	126.82
1998	135.56
1999	142.33
2000	151.32
2001	152.9
2002	158.19
2003	157.18
2004	160.81
2005	164.45
2006	170.6
2007	179.42
2008	187.48
2009	195.88
2010	203.58
2011	209.2
2012	214.61
2013	220.45
2014	225.37
2015	231.19
2016	236.93