Well, there are search engine bots that "view" posts, so that may not necessarily mean anyone listened.
But I did. I don't want to assign a number, but it's below average. Most of the time you can sing on pitch, and the times you don't it's because of the technical issue you are having with your vowel clarity and not tone-deafness.
With regards to vowels: they are an acoustic property of the voice. Imagine you have an acoustic guitar or violin or trumpet. They all have a shape to them that helps make their sound distinct. If you had a square guitar, for example, I'm sure it would change the sound quite a bit, and most likely make it less somehow.
So each vowel we use has a distinct shape as well. The shape is created by the tongue, the pharynx (the space above the larynx), or a combination of both. When those things are not trained correctly, you begin to sound like you have marbles in your mouth, or just had a procedure at the dentist and the novocaine hasn't worn off. It also causes notes to sound flat and not to project strongly.
There are some other issues, but that's the main one. You will need a good teacher and lots of patience.
