Year	Number of
1990	127.92
1991	132.68
1992	139.29
1993	145.49
1994	153.05
1995	158.88
1996	162.72
1997	170.85
1998	177.22
1999	181.03
2000	189.59
2001	181.61
2002	201.58
2003	208.45
2004	212.71
2005	216.14
2006	219.15
2007	225.44
2008	233.16
2009	241.12
2010	250.97
2011	263
2012	273.66
2013	285.55
2014	299.23
2015	313.52
2016	330.01