Peak flow

Hi. Has anyone ever measured their 'peak flow'? It's the sort of thing you do if you suffer from asthma. I suffered somewhat when I lived in London. I can't remembered what my peak flow was then, but its about 570 now. Anyone else got any numbers? (There's a website that tells you what 'normal' is if you type in your age, gender and height. Apparently mine should be between 615 and 630.) Quentin