Formula help for metrics with different thresholds - very difficult problem

I can usually figure stuff out, but need help on this one.

I have groupings of metrics with thresholds for example

0-52 would be level 1
53-60 would be level 2
61-78 would be level 3
79-82 would be level 4
83 and above would be level 5

what I am trying to do is figure out how to calculate this. Some examples of expected results;

If the person scored 53 he would be at level 2 or approximately 2.0
If the person scored 59 he would be at level 2 or approximately 2.9
If the person scored 61 he would be at level 3 or approximately 3.0
If the person scored 81 he would be at level 4 or approximately 4.5
If the person scored 84 he would be at level 5 (max would always be 5, could not have 5.3)

The thresholds are always in groups of 5 and from 0-100
The thresholds can be different, so it has to be some kind of formula
I dont need the level, I need the actual percent (out of 5) that they are; like 4.23 or 2.75

Has anyone come across anything like this? At the end of the day, since there are 5 metrics, each one is approximately 20%, so I am thinking i have to convert the threshold to percent of a 5th, but that has not worked for me so far.

Any help or ideas, similar threads, anything at all would be appreciated.

That would give me the level, but I need to find the percentage of the level, if that makes sense. So are they at 3.0, 3.5, 3.9..

Its very confusing, so hopefully I am explaining it well.

In the attached file I've set up a little table in M1:N5 showing your thresholds and the levels. I've used column A for the scores in your example above, and this formula is in B2:

=IF(A2>=$M$5,5,MATCH(A2,$M$1:$M$4)+(A2-INDEX($M$1:$M$4,MATCH(A2,$M$1:$M$4)))/(INDEX($M$1:$M$5,MATCH(A2,$M$1:$M$4)+1)-INDEX($M$1:$M$4,MATCH(A2,$M$1:$M$4))))

which is then copied down as far as is necessary.

Hope this helps.

Pete