RATIO_TO_REPORT
RATIO_TO_REPORT computes the ratio of a value to the sum of a set of values. If expression1 evaluates to NULL, the ratio-to-report value also evaluates to NULL.
Syntax
RATIO_TO_REPORT (expression1) OVER ( [ PARTITION BY expression2 [, ...] ] )
Remarks
• PARTITION BY is optional.
• The window clause is not allowed.