Common nomenclature is to set copper conductivity at 1.0 and compare others on this scale. Silver is the only metal more conductive than copper at 1.07. However, I do stand corrected. Looking this up I see silver listed as 1.05 to 1.07 so 1.06 is quite reasonalbe. I’ve always remembered 7%.
Other metals:
gold .70
aluminum .61
brass .28
steel .10