Not that the members here are representative of the total amount of iPhone owners in the world but the poll here indicated it was almost 50% of users who had the issues. Also the issue is happening worldwide. Your number of less than 1% is way off base.
A poll on a forum, where likely anyone who has a problem will go?
I would be willing to guess the issue affects between 1-5% of iPhone 4 users, and probably 1-5% of iPhone 3GS users. Personally, I know atleast 7 people who own the phone in real life, and none have had any complaints.