I don't think that's correct. I think that a sizable minority of black voters voted to keep the flag. IIRC, it was about 15% or so, maybe higher. (???)
I am not sure you figure it out and get back to me . :>)
A look at the poll results is revealing. Of those 25 counties with black majorities, nine counties voted for the 1894 flag. This calls into question the alleged racial divide on the flag. News accounts give the impression that all white votes went for the 1894 flag and all black votes went for the new proposal. Not true, as it turns out.
In fact, a significant section of the white votes voted for the new proposal. Two counties with majority white populations voted for the proposed flag. "The 1894 flag would simply not have won by a 65% landslide unless a significant number of black citizens voted for it."
In Humphreys County, where the population is above 70% black, 47% voted for the current flag. Coahoma, Leflore, Sunflower and Washington Counties, with a white population of only less than 40%, registered votes favoring the 1894 flag around 49%.
Of the eleven counties having between 60% and 70% black populations, the 1894 flag carried three and received from 46% to 49% of the vote in four counties and received less than 41% of the vote in two.
Therefore the big story the national press is ignoring is that the old flag, dominated by the Confederate battleflag image, enjoys broad biracial support in Mississippi.