reduce tax rate by 1%

How would I reduce the tax rate by 1%   Example below:

CITY      Tax Rate      ZIP      County
Ahwahnee      8.75      93601      Madera
Alameda      9.75      94501      Alameda
Aliso Viejo      8.75      92656      Orange
Alturas      8.25      96101      Modoc
Alviso      9.25      95002      Santa Clara
Amador City      8.75      95601      Amador
American Canyon      8.75      94503      Napa
Anderson      8.25      96007      Shasta
Angels Camp      8.25      95222      Calaveras
Angwin      8.75      94508      Napa
Antioch      9.25      94509      Contra Costa
Aptos      9      95003      Santa Cruz
Arcata      9      95221      Humboldt
Atwater      8.25      95301      Merced
Auberry      8.975      93602      Fresno
Auburn      8.25      95602      Placer
Auburn      8.25      95603      Placer
Bakersfield      8.25      93304      Kern
Bakersfield      8.25      93307      Kern
Bakersfield      8.25      93308      Kern
Bakersfield      8.25      93309      Kern
Bass Lake      8.75      93604      Madera
Belmont      9.25      94002      San Mateo
Ben Lomond      9      95005      Santa Cruz
Benicia      8.375      94510      Solano