Year	Number of
1990	54.92
1991	56.96
1992	58.74
1993	60.26
1994	62.17
1995	63.9
1996	65.75
1997	67.24
1998	69.17
1999	70.17
2000	70.95
2001	70.52
2002	70.63
2003	72.05
2004	73.65
2005	74.85
2006	76.8
2007	78.98
2008	82.41
2009	86.13
2010	90.37
2011	94.83
2012	99.4
2013	104.52
2014	109.83
2015	115.35
2016	120.99