Year	Number
1992	7.87688
1993	7.94756
1994	7.64388
1995	7.32
1997	8.15747
1999	12.79513
2000	10.508
2001	10.82271
2002	10.89564
2003	11.31134
2004	11.8343
2005	12.6695
2006	12.91192
2007	13.21255
2008	13.76223
2009	13.89771
2010	14.02471
2011	14.33903
2012	13.84212
2013	13.38304
2014	16.23723
2015	14.5663
2016	15.08347
2017	14.42158
2018	13.86492