Best way to store not publicly viewable data? I wanted to know what is the most suited to store not publicly viewable data? Here is an example what I want to achieve:

Imagine having a personal section about me. On this site I show the visitors an online CV which includes a section of my skills. In the section "skills" I have listed each skill with a specific rating like 8/10 depending on how good I'm in it. 

For helping you to visualize it, here is a normal CV with a section skills:

https://creativemarket.com/GraphicsToll/492647-Resume

Now my question is how do I store this kind of data? I know that a normal custom content type would be an overkill because not one of the skills should be separately viewable, it should be only visible with all the other skills on my online CV. Further I looked into custom content entities but I think this also an overkill because you could also view each skill separately (canonical).

What other ways are there? Do I have to create a module which just interacts with the database abstraction layer? 

I appreciate any kind of help!
The simplest way to do this is to put the two fields "skill name" and "rating" in a field collection:

Field collection

But I would suggest to use the new module Paragraphs. This will extent Drupal's flexibility to design content types for structured data a lot:

Paragraphs

Edit:

Changed module name (thanks to @Berdir).