Here are the stats on reviews for the group stage for each umpire:
Aleem Dar:
Decisions reviewed: 7
Upheld: 5
Reversed: 1
Umpire's Call: 1
Kumar Dharmasena
Decisions reviewed: 9
Upheld: 7
Reversed: 2
Marais Erasmus
Decisions reviewed: 2
Upheld: 2
Chris Gaffaney
Decisions reviewed: 8
Upheld: 2
Reversed: 4
Umpire's Call: 2
Ian Gould
Decisions reviewed: 4
Upheld: 1
Reversed: 3
Richard Illingworth
Decisions reviewed: 5
Upheld: 2
Reversed: 2
Umpire's Call: 1
Richard Kettleborough
Decisions reviewed: 7
Upheld: 1
Reversed: 4
Umpire's Call: 2
Nigel Llong
Decisions reviewed: 3
Upheld: 1
Reversed: 1
Umpire's Call: 1
Bruce Oxenford
Decisions reviewed: 5
Upheld: 3
Reversed: 2
Sundaram Ravi
Decisions reviewed: 4
Upheld: 3
Reversed: 1
Paul Reiffel
Decisions reviewed: 3
Upheld: 2
Reversed: 1
Rod Tucker
Decisions reviewed: 2
Upheld: 2
Michael Gough
Decisions reviewed: 6
Upheld: 4
Umpire's Call: 2
Ruchira Palliyaguruge
Decisions reviewed: 9
Upheld: 3
Reversed: 4
Umpire's Call: 2
Joel Wilson
Decisions reviewed: 5
Upheld: 2
Reversed: 1
Umpire's Call: 2
Paul Wilson
Decisions reviewed: 10
Upheld: 3
Reversed: 4
Umpire's Call: 3
These stats only reflect decisions that were reviewed - from what I saw, there were a number of calls that should have been reviewed but weren't - either because the team chose not to review, or couldn't (because they'd used their review already).