Because the usage is percentage based, of course it depends entirely on which CPU you currently have. I imagine 3-5% of the latest Macbook Pro Retina i7, isn't

Because the usage is percentage based, of course it depends entirely on which CPU you currently have. I imagine 3-5% of the latest Macbook Pro Retina i7, isn't the same as the 2010 Macbook Air's Core 2 Duo.