SQL根据表中的现有数据计算百分比并进行更新

I have table as below with all the fields except percentage. Based on the total Number of cases I need to calculate percentage for each case id. For easy interpretation I choose numbers as below. So the total cases for all the caseids is 100, out of which case id as 35 cases so its percentage is 35. What script can I use to get those total percentage values and update in table accordingly.I have table as below with all the fields excep