Year	Number of
1990	53.82
1991	54.01
1992	55.9
1993	58.75
1994	61.93
1995	65.04
1996	66.26
1997	67.43
1998	68.28
1999	68.93
2000	69.8
2001	70.95
2002	72.48
2003	74.01
2004	76.67
2005	77.39
2006	79.52
2007	82.38
2008	85.34
2009	87.11
2010	89.83
2011	91.75
2012	94.45
2013	97.13
2014	100.05
2015	103.16
2016	106.6