"OFC" is a pretty overused term and, in fact NO cable is oxygen fee. That would make the conductor 100% copper, which isn't realistic.
The best you an get is 99.999% copper but the norm is generally somewhere around 99.9% copper, but they generally don't tout it. All are morethan adaequate for home use.
Here's a little primer. in simple terms, to give you a little background on this.