I have to calculate percentage of a column , Created a calculation field for it . The problem is if is select date filter for 1 day the percentages are showing correct , when ever I'm trying to change the Range for 2 or more days

I have to calculate percentage of a column , Created a calculation field for it . The problem is, if I select date filter for 1 day the percentages are showing correct , when ever I'm trying to change the Date Range for 2 or more days ,the percentage is showing incorrect (there is at least 3 % variation) in each bar ,Can some one help with this.