Year	Number of
1990	111.9
1991	117.75
1992	124.03
1993	131
1994	138.55
1995	146.74
1996	154.29
1997	162.36
1998	171.19
1999	180.48
2000	190.26
2001	203.15
2002	216.97
2003	232.43
2004	248.92
2005	266.56
2006	282.12
2007	298.36
2008	316.2
2009	335.22
2010	355.67
2011	378.62
2012	403.45
2013	430.42
2014	459.09
2015	489.45
2016	522.08