April 1987

12.00%

May 1987

11.00%

May 1988

9.45%

August 1988

11.25%

October 1988

12.50%

January 1989

13.25%

November 1989

14.25%

March 1990

15.15%

November 1990

14.25%

April 1991

13.50%

May 1991

12.70%

July 1991

12.20%

August 1991

11.70%

October 1991

11.25%

March 1992

10.85%

July 1992

10.55%

November 1992

9.90%

December 1992

9.20%

January 1993

8.50%

April 1993

7.95%

April 1994

7.64%

October 1994

8.10%

January 1996

7.44%

April 1996

7.20%

August 1996

6.99%

January 1997

7.24%

June 1997

7.55%

September 1997

8.35%

October 1998

8.85%

December 1998

8.05%

February 1999

7.30%

March 1999

6.80%

February 2000

7.24%

April 2000

7.45%

March 2001

7.20%

May 2001

6.95%

June 2001

6.70%

October 2001

6.45%

November 2001

5.95%

January 2002

5.45%

April 2003

5.35%

January 2004

5.60%

March 2004

5.85%

June 2004

6.10%

July 2004

6.35%

September 2004

6.60%

September 2005

6.35%

September 2006

6.60%

December 2006

6.85%

February 2007

7.10%

June 2007

7.35%

October 2007

7.60%

January 2008

7.35%

March 2008

7.10%

May 2008

6.85%

December 2008

5.85%

January 2009

5.35%

February 2009

4.99%

April 2009

4.74%

March 2010

5.19%