Help Creating New Column From Summing Another Column



What I am trying to do seems pretty straighforward, but due to my lack of knowledge/experience, I am having a hard time getting it.


I have card that displays the total contract value of of projects assigned to a particular project manager/employee for a given time period. My goal is to create a new column that displays what percentage of the total current contract amount for the whole company each project manager/employee is currently assgined. The issue lies in the fact that I currently do not have a column/measure summing up all current projects by their contract values. So essentially how can I sum the entirety of a column for a given time period in order to use that value for other equations?


My card looks something like this....

Project Manager# of JobsOriginal Contract AmountCurrent Contract Amount 
Jim Smith167,099,960.158,476,897.67
Steve Smith217,963,172.008,392,763.00
Joe Smith187,561,849.407,733,761.86