Year	Number
1994	22.1074
1995	22.19168
1996	22.17949
1997	22.26834
1998	22.50231
1999	22.6895
2000	22.31554
2001	21.94032
2002	21.82722
2003	20.78876
2004	19.78871
2005	19.31172
2006	19.12671
2007	18.85136
2008	18.78618
2009	18.26421
2010	17.86192
2011	17.56508
2012	17.60064
2013	17.1291
2014	17.23955
2015	17.85319
2016	18.58163
2017	18.26711
2018	18.09996