Percentage based on the value of a dimension

[Jesus_Lagos]

Based on the image I want to calculate in a pivot table the percentage based on the first month.
For example:
- For the first row calculate 51.968/51.968, 49.471/51.968, 50.783/51.968,....
- For the second row 0, 146.687/146.687, 143.894/146.687, 127.958/146.687..