Year	Number
1974	33.8964
1983	32.391
1984	30.81498
1985	32.44269
1987	30.95916
1988	31.79701
1989	21.29086
1990	30.52195
1991	34.14243
1992	33.83432
1993	24.04492
1996	24.55948
1998	25.47402
1999	26.93516
2000	27.38091
2002	22.53468
2003	21.37896
2004	22.78988
2005	22.63092
2006	22.37218
2007	23.88368
2008	22.5478
2009	18.1105
2010	17.82338
2012	19.50235
2013	18.976
2014	17.90055
2015	16.58534
2016	16.46366
2017	15.3206
2018	18.11021