Existing Home Sales Fall Much More Than Expected In July

*Canadian Dollar Slumps To Nearly 16-month Low Of 78.47 Against Yen

*Aussie Slides To 15-day Low Of 1.2539 Against NZ Dollar

*Mexico July Exports Rise 29.5% On Year, Imports Up 26.5%

*Australian Dollar Drops To 4-day Low Of 1.4364 Against Euro