Oracle PL/SQL Tutorial/Statistical Functions/Cume Dist
Cume_Dist calculates the cumulative probability of a value for a given set of observations
It ranges from 0 to 1.
The general format for the CUME_DIST function is:
<source lang="sql">
CUME_DIST(expr [, expr] ...) WITHIN GROUP (ORDER BY expr [DESC | ASC] [ NULLS {FIRST | LAST }] [, expr [DESC | ASC] [NULLS {FIRST |LAST }]] ...)</source>