Just so that you can have a clearer idea about the reasons for the comments, think about two different types of websites, one is mostly informational (i.e. lots of text, images, etc.) while the other is transactional (i.e. lots of workflows, buttons and call-to-actions).
Lets look at the informational site first. If your content is mostly short snippets of information split into many pages then there will be a bias towards a higher navigation to content ratio. But you can easily change this by using a different container or structure for your content (e.g. accordion). If you are looking at the ratio from the perspective of the physical viewing space on the screen versus the logical viewing space for the entire page (i.e. including the scrolling or swiping you can do), then that ratio will change. You can also reduce the navigation space on mobile by the use of a collapse menu icon.
On the other hand, in a transactional site ideally you will want separate and discrete steps for the transactions, so you may not have so much control over this. However, if you stick to good content design practices you will find that the IA is simpler and easier to present nicely, thus saving the amount of space that the navigational elements should take up. But you do have to account for the fact that page navigation elements will take up additional space on the page.
Therefore, it is not easy to say what the best ratio should be, but that you should start with good content design practices and then you'll find that what you are left with is going to be the optimal solution (or close to it).