Year	Number
1983	15.93865
1984	15.82434
1985	16.973
1986	16.70163
1987	16.70203
1988	16.05084
1989	15.60032
1990	15.68562
1991	15.35704
1992	15.30451
1993	15.96673
1994	15.85369
1995	16.22553
1996	16.47861
1998	17.95005
1999	17.25853
2000	17.41596