Summary Fields and Relationships

You need to at least have a relationship between the two tables so that the Project Revenue table is a child to the Total Revenue table. Then you can make things a lot easier because:

1. You will not have to enter the Total Revenue. Instead, you would have summary fields for each month's field from the Project to the Total
2. You can then do a formula on the Total table to get the Total Revenue for the Year value and take that down to the Project table as a Lookup.
3. Using the Lookup from the Total, you can build a formula to calculate the % of Total for each Project 
4. You can create a Summary Report on the Projects table (with no filter) that shows the % of Total for each Project and then use that report as an embedded report on the Total's record to show the associated Projects