Year	Number of
1990	92.52
1991	103.52
1992	115.94
1993	128.95
1994	144.11
1995	162.03
1996	165.18
1997	169.17
1998	174.17
1999	179.18
2000	184.11
2001	182.14
2002	180.36
2003	181.19
2004	182.24
2005	183.58
2006	187.33
2007	190.99
2008	194.81
2009	198.81
2010	203.15
2011	205.73
2012	208.66
2013	211.73
2014	214.94
2015	218.3
2016	221.87