Year	Number of
1990	157.62
1991	161.53
1992	165.98
1993	170.99
1994	176.4
1995	182.5
1996	185.99
1997	189.96
1998	194.14
1999	198.51
2000	203.15
2001	209.39
2002	216.45
2003	224.17
2004	232.45
2005	240.7
2006	246.98
2007	253.69
2008	261.46
2009	270.18
2010	279.58
2011	290.13
2012	301.58
2013	313.76
2014	326.43
2015	339.77
2016	352.25