Year	Number of
1990	48.2
1991	53.01
1992	58.09
1993	61.71
1994	66.23
1995	72.02
1996	77.71
1997	85.09
1998	86.76
1999	88.07
2000	88.63
2001	89.79
2002	93.08
2003	92.45
2004	94.09
2005	95.79
2006	98.28
2007	101.59
2008	103.37
2009	106.95
2010	108.85
2011	110.55
2012	114.77
2013	118.38
2014	121.93
2015	125.55
2016	128.94