which era had the highest ratio of crooked top level fights?
the lack of convictions makes much of this guesswork on my part, i have not included too many individual fights as it would distract from the question.
bareknucklers were fighting illegal fights with a low volume of illegal gambling(ringside basically), lots of room for foul play tho, although the loser(and often winner) tended to sustain obvious damage, i would think the early finishes/claimed injuries were the most suspect fights. the reporting on suspected fixed fights was vocal, to an extent that would be impossible today.
the early 1900's had a number of bouts that caused press scandal, they likely weren't all crooked but some must have been, lots of good points on this in the race based thread. referee's being sole judges makes a easy target for gamblers or managment looking for influence. the relatively low purses for most fights works both ways, fighters need money but they know they also need future fights so should be wary of making it too obvious.
20/30's to 50's the italian organised crime era, carnera had fights fixed for him, although his title win seems legit, also lamotta fox was in '47. standard logic says this era would have the most, but it also had more fights overall. i have seen a quote that over 50% of fights in NY in the 40's were fixed but that seems so high i dont believe it. the depression, and the poverty it caused must have led to name fighters needing the money and being influenced.
the 60's to 80's aint my favorite era of history, so i spent most of this morning reading about this, organised crime didn't seem have the same control as previously in america but was obviously still present. An italian crime boss is said to have owned a % of the middleweight title during this time. i could go on for ages about don king, sanctioning bodies and corruption but yous know it anyway(or search for some of senor pepe's threads)
90's to modern day, more legal gambling options allows fighters to collude without deciding the outcome, although mismatches(a basically decided outcome) are the obvious place to do this. haye harrison is the only fight ive been told would be fixed before hand that looked like it was(although the same guy told me haye would throw klitchsko but i didn't and dont believe that).
the rise of eastern european fighters has happened at the same time as the rise in eastern european organised crime, but they're slick and not media friendly like the N.american mob, so the obvious conclusions(that some of the fighters will have shady backers) can only be guessed at.
my conclusion: the highest % was probably around the 40's but i doubt its that much higher than throughout the rest of boxing history