Year	Number
1977	25.38636
1980	18.83036
1999	15.45933
2000	14.49367
2001	15.16667
2002	14.9125
2004	13.39044
2005	12.80632
2006	12.1014
2007	11.06269
2008	12.09061
2011	12.07576
2012	13.31023
2013	13.0363
2018	15.74725