Year	Number
1994	17.59746
1995	17.57782
1996	16.57274
1997	16.37894
1998	16.72227
1999	17.04818
2000	17.18382
2001	17.35586
2002	17.5442
2003	18.06622
2004	19.09583
2005	18.34531
2006	17.20934
2007	15.8808
2008	14.88578
2009	14.32575
2010	14.4183
2011	14.51438
2012	14.28247
2013	14.02068
2014	14.1397
2015	13.80136
2016	13.36758
2017	13.87843
2018	13.86854