Year	Number
1990	12.26314
1991	9.03192
1992	7.9135
1993	6.53961
1994	7.12663
1995	7.86133
1996	8.08088
1997	7.84589
1998	8.84191
1999	8.72839
2000	8.65611
2001	8.38231
2002	8.28946
2003	10.20143
2004	10.23344
2005	10.91037
2006	10.34357
2007	10.36744
2008	10.13191
2009	9.94566
2010	11.22189
2011	11.36477
2012	11.4244
2013	13.74758
2014	10.85659
2015	10.09944
2016	9.72915
2017	9.71654