Warning! Performance monitoring and scales in Windows have perplexed many, many people and you will be hard pressed to find a definitive source of information. Having said that, I'll at least give you what I know.
Each counter returns its own values. Sometimes it's a percent, sometimes its an integer.
If it's a percent, things can get confusing because some counters will aggregate multiple instances of a sub-system and present the number as something greater than 100%. For example, I think its
process(_total)\%processor time average that will take each core, add what percentage of usage it's under, and then can present you with a number greater than 100%. Four cores with 50% usage will be represented by the number 200.
If it's an integer, then it's wholly up to you to figure out what number is actually returned, based on either the name of the counter, or the documentation that may or may not be associated with it. Is it returning Megabytes, Megabits, bps, fps, gps, pps? Who even knows. You have to figure that out first. Once you do, what the base number will be ($n x 1.0) will then make sense. At that point you can then scale it to be viewable in whatever number you want. So for example, a counter that returns Mbps will show you a 5Mbps load as 5.0. Do you want to see it broken down finer? Then scale it to 10 or 100.
As for what the scale on the left of Permon is, remember that you could place any number of different counters, counting any number of different metrics in any number of different scales. There's no way that a scale could accurately reflect any kind of correlation between them all.I haven't yet found a way to use that scale to any positive effect when multiple types of metrics are being graphed at multiple scale. Sad to say, there is still lots left to be explained about perfmon's behavior.
P.S. "Current Bandwdith" will always be at 100 because your NIC is 100BASE-T. You probably want to look at the Bytes Received and Bytes Sent counters.