[dragonwriter]

All the white people I know (since knowing people takes "actual interaction") have spoken to a black (or, at least, a multiracial person with black enough features to be generally considered "black" by observers) person enough to meet that standard, pretty much by definition.

But, while I think your 90% number is a substantial exaggeration, you do make a good point that this is probably far less common than most people think it is.