Year	Number
1998	24.02238
1999	24.54011
2000	23.76711
2001	25.06435
2002	25.59191
2003	25.27768
2004	25.5988
2005	25.97657
2006	26.13269
2007	26.00028
2008	26.5076
2009	26.58463
2010	26.14485
2011	25.8153
2012	26.7125
2013	26.11771
2014	26.06809
2015	25.76868
2016	25.99001
2017	25.35299