Year	Number of
1990	32.09
1991	33.7
1992	35.37
1993	37.69
1994	39.85
1995	42.32
1996	44.17
1997	45.57
1998	46.99
1999	49.14
2000	51.28
2001	52.96
2002	55.78
2003	58.9
2004	63.82
2005	69.94
2006	72.97
2007	75.96
2008	79.97
2009	85.52
2010	90.07
2011	94.92
2012	99.49
2013	102.83
2014	106.46
2015	110.03
2016	113.5