At least for the top 5. Let's take a look at the finishing rate of every division's top 5.

* Note : I will be accumulating the average by fighter's percentage, not per fight. This may alter the results.

Heavyweight 84%

1) Junior Dos Santos 86%

2) Cain Velazquez 90%

3) Daniel Cormier 70%

4) Alistair Overeem 94%

5) Fabricio Werdum 81%

Light Heavyweight 63%

1) Jon Jones 81%

2) Dan Henderson 51%

3) Rashad Evans 47%

4) Lyoto Machida 50%

5) Shogun Rua 90%

Middleweight 67%

1) Anderson Silva 78%

2) Chris Weidman 66%

3) Chael Sonnen 40%

4) Vitor Belfort 80%

5) Tim Boetsch 75%

Welterweight 73%

1) Georges St. Pierre 59%

2) Carlos Condit 92%

3) Johny Hendricks 61%

4) Martin Kampmann 75%

5) Nick Diaz 80%

Lightweight 52%

1) Ben Henderson 58%

2) Gilbert Melendez 57%

3) Gray Maynard 18%

4) Frankie Edgar 42%

5) Nate Diaz 87%

Featherweight 60%

1) Jose Aldo 71%

2) Chad Mendes 41%

3) Pat Curran 58%

4) Ricardo Lamas 50%

5) Chan Sung Jung 84%

Bantamweight 71%

1) Dominick Cruz 36%

2) Renan Barao 65%

3) Urijah Faber 80%

4) Brian Bowles 90%

5) Michael McDonald 86%

Flyweight 54%

1) Demetrious Johnson 60%

2) Joseph Benavidez 75%

3) Ian McCall 63%

4) Yasuhiro Urushitani 26%

5) Jussier da Silva 50%

So in conclusion

1) Heavyweight 84

2) Welterweight 73

3) Bantamweight 71

4) Middleweight 67

5) Light Heavyweight 63

6) Featherweight 60

7) Flyweight 54

8) Lightweight 52