Year	Number
1985	13.11203
1986	13.14208
1987	13.99569
1988	14.67833
1989	14.8146
1990	16.55999
1991	16.79118
1992	17.71099
1993	17.98746
1994	18.4989
1995	18.55566
1996	18.38424
1997	18.3018
1998	18.56353
1999	18.9924
2000	18.6396
2001	18.12789
2002	16.65273
2003	15.73699
2017	10.05717
2018	10.37394