Pivot Chart not showing right values

Difficult to say from the picture, but I notice that your Y axis appears to be formatted "0" with no decimals, so there are two gridlines labeled 98% (I would guess the lower one is actually 0.975 and the upper one is 0.980). Same for 99% and 100%. I would guess that your data labels are also rounded to the nearest hundredth (integer per cent), but that the actual values being plotted are more precise. You need to look at your data and determine the exact value being plotted for each column, because I suspect that what you believe is the same value is not actually the same value.