1st January 1986–31st December 1998

72.4%

1st January 1987–31st December 1998

67.3%

1st January 1988–31st December 1998

60.5%

1st January 1989–31st December 1998

51.9%

1st January 1990–31st December 1998

41.1%

1st January 1991–31st December 1998

27.3%

1st January 1992–31st December 1998

22.2%

1st January 1993–31st December 1998

18.0%

1st January 1994–31st December 1998

15.9%

1st January 1995–31st December 1998

13.4%

1st January 1996–31st December 1998

9.2%

1st January 1997–31st December 1998

6.9%

1st January 1998–31st December 1998

3.2%

(all dates inclusive)