One of the official sources (and this would've been back in 3rd Edition) points out that muggings have decreased because of the chance of people being augmented or magical and turning the tables on their attacker.
I can't say exactly what amount of people would have some amount of magic or cyberware that would make them able to deter a mugger, but here's what we know:
As TimothyAWiseman pointed out in his answer, datajacks are pretty common. This was especially true in 3rd Edition, but their prevalence probably hasn't gone down. In addition, cosmetic modifications are common among those who can afford them, and people may acquire some cyberware or bioware to replace injured tissue (for instance, a cyberlimb after an industrial accident, or a synthacardium following a heart attack), though typically replacement parts would be more oriented toward normal functionality and not cyborg super-soldier sorts of gear, unless the person in question is a member of those rich enough to just get whatever top-end is available.
But there are also other reasons to get augmentations; a lot of people would get enhanced vision (either to compensate for poor vision or just to be able to see with magnification), or even just for kicks, since some of the low-end cyberware isn't that much more expensive than some other consumer goods (and some can theoretically be argued to fall into lifestyle costs) for middle/upper-class; it'd be like the difference between having a cell phone and smart phone but for your body.
In addition, 4th Edition mentions that a lot of people who would originally seem likely candidates for augmentation (security officers) usually just get drugs or the like to augment themselves, rather than actually using chrome or bioware, since they're cheaper and if your guy burns out early you don't have to promote him/pay as much pension.
So in short, we can't really assume a statistic, because it's pretty likely that there's a large population of people with cyberware or bioware in them (more if you include cloned organs in the bioware category), but few of them will have any significant ones. As for people who are Adam Jensen style combat cyborgs, you're looking at a really tiny population with a decent turnover rate.