Year	Number of
1990	110.1
1991	111.22
1992	105.54
1993	100.01
1994	96.92
1995	95.84
1996	102.64
1997	110.62
1998	124.14
1999	135.89
2000	142.05
2001	141.29
2002	139.41
2003	136.07
2004	134.29
2005	134.44
2006	139.52
2007	144.38
2008	151.12
2009	158.54
2010	166.08
2011	171.34
2012	175.6
2013	184.42
2014	193.62
2015	204.3
2016	214.68