It's pretty serious for the five people who get bitten every day. To me, one attack is too many.
Having said that, this figure, I think, is postmen. And certainly I would make the simple rule of "keep your dog in, or you don't get mail".
Keep in mind that's just 5 from one profession every day.
There are about 90k posties in the uk so that's approximately 2% recording dog attacks every year.