Year	Number
1986	24.52438
1987	24.91787
1988	24.77279
1989	24.67967
1990	24.48637
1991	24.35376
1992	24.26625
1993	23.93547
1994	23.69068
1995	23.32331
1996	23.22972
1997	22.35308
1998	22.74732
1999	22.56459
2000	22.86407
2001	23.97166
2002	23.65336
2003	24.24492
2004	24.3755
2005	24.35625
2006	24.23172
2007	22.89481
2008	24.51989
2009	25.56382
2010	24.56905
2011	24.78159
2012	27.28919
2013	27.16603
2014	26.43348
2015	26.05089
2016	25.37499
2017	25.05847
2018	25.12662