Highlight Lowest 8 of the last 20 numbers in a column - Golf Handicap

The method for calculating golf handicap (Index) has recently been changed by the World Golf Association. I am building a sheet to calculate a golfers Index. The calculation uses the lowest 8 net scores from your last 20 games. You continually make the spread sheet larger each time you add a new game so the 21st game drops off and the new one gets considered in the calculation. The formula that I use is as follows " =AVERAGE(SMALL(I29:I48,{1;2;3;4;5;6;7;8})) ". It seems to be working in that it takes the lowest 8 of the last 20 numbers in the Differential column.

I would like to highlight the 8 numbers in the Differential column that are being used to calculate the index. I have been struggling with that part. Any suggestions?

I was going to let my friends use it (any members of this post are welcome to use it also). In giving it, out it would be better if one did not have to replicate additional lines when the table is full. In other words make it friendly to non-Excel people (Dummy proof it). Any suggestions on that would be appreciated too.

If any golfers see anything technically wrong with it that I have missed, please let me know.

This is my first post and I hope that I have followed the rules correctly and am clear with my request.

Thx
Eddy the SF

Eddy the SF . Could you please clarify this

8 numbers in the Differential column that are being used to calculate the index.

It is ok for first range, but not next. I mean a value can by 9th for first calculation and 8th for next. Let see 1,2,3,4,5,6,7,8,9,10 - for 1st 1-8. 2nd 2-9 3rd 3-10 ,,, all must be highlighted.