Year	Number
1996	20.19546
1997	20.3025
1998	21.53607
1999	20.47004
2000	21.00501
2001	21.96428
2002	21.98517
2003	26.08306
2004	28.10696
2005	30.52121
2006	28.4495
2007	30.62803
2008	35.65333
2009	33.40011
2010	27.18819
2011	27.04753
2012	27.12671
2013	26.17444
2014	25.53533
2015	26.14051
2016	28.86631
2017	26.76263
2018	27.87912