Year	Number
1999	29.1812
2000	29.71766
2001	29.98227
2002	30.79411
2003	30.48365
2004	30.38288
2005	30.95801
2006	30.77744
2007	28.31265
2008	29.70698
2009	29.22803
2010	28.30391
2011	28.96462
2012	30.07819
2013	29.99385
2014	29.5964
2015	30.22972
2016	30.32114
2017	30.53249