adding mean and standard deviation values to chart while having % values

If I'm understanding this correctly, then I think that the issue is that your percentages are proportional, which means the mean of the percentages will always be 20%, since there are 5 values totaling 100%, and the STDEV is calculating the STDEV of those percentages, not the STDEV of the raw data. I think what you want is to calculate the mean and STDEV of the raw total, as you've done in column D, then get the proportional percentage of that STDEV to use on the chart. In the attachment, I've added some headers in row 4 to simplify the formulas, then I used the following in L6 to get the proportional percentage of the mean for each section:

=IF(H6="",NA(),AVERAGEIF($A$2:$A$50,L$4,$B$2:$B$50)/COUNTIF($A$2:$A$50,L$4))

Fill the formula right through column N and down through row 20 and you should have your averages. For the mean, use the following formula in P6 where it should be array-confirmed (use Ctrl + Shift + Enter instead of Enter):

=IF(H6<>"",L6-STDEV(IF($A$2:$A$50=P$4,$B$2:$B$50))/COUNTIF($A$2:$A$50,P$4),NA())

Fill right and down, then use the following formula (array entered) in T6:

=IF(H6<>"",L6+STDEV(IF($A$2:$A$50=T$4,$B$2:$B$50))/COUNTIF($A$2:$A$50,T$4),NA())

Fill right and down. The results seem to align better with what (I think) you're after. Take a look at the attachment to see if it's a good fit: