Does anyone have any suggestions on how to give the scores?

Example 1,
under column A, there is a list of values.
7,6,-5,-10,9,-3,8,1,0,0,2,10

I would like to give the score to each value under column B.
The range for values is found from -10 to 10 through the given numbers.
100% should be given for -10, and
0% should be given for 10,
50% should be given for 0, because it is in the middle of the range.
75% should be given for -5
The rest of score should be given based on the position within the range.

Example 2,
under column A, there is a list of values.
-20,0,-5,10,7,8,-2

I would like to give the score to each value under column B.
The range for values is found from -20 to 10 through the given numbers.
100% should be given for -20, and
0% should be given for 10,
50% should be given for -5, because it is in the middle of the range.
25% should be given for 0
The rest of score should be given based on the position within the range.

Does anyone have any suggestions on how to determine the scores in Excel?
Thanks in advance for any suggestions
Eric