I will tell you the trueth. There is no way to know. Not every book deer killed is entered, or for that matter, publisized.
But one could find the totals off the DWR site of the number of bucks killed in a year, then look up the number of bucks recorded for that year in the B&C record book, and then like you said, guess.
I will tell you a fact. No amount of research will give you a number above 1/4 of 1 percent.
That's 1 in a thousand.
Homer is probably correct "NOT EVEN 1/10 of 1%" but it will be interesting what the OP comes up with through his research.
We see so many big buck through all forms of social media bombardment that we think they're more common than they actually are.
Thousands and thousands of small to average bucks will be killed for every B&C contender.
Of course just my 2 cents.
Zeke