Year	Number
1973	12.96239
1976	12.90747
1977	12.38057
1978	12.93156
1979	13.86908
1980	11.81683
1984	14.08528
1985	14.58099
1986	14.76291
1987	15.02734
2000	23.56872
2001	23.80399
2002	24.67456
2003	26.38547
2004	22.00003
2013	21.53122
2014	24.47279
2015	24.28976
2016	23.74541
2017	24.43582
2018	24.72586