It's how many people have clicked a link, not necessarily how many full downloads you've had. If you have a look at your site's logs you can see that.
For instance, our logs are at http://www.pearsallrampage.co.uk/logs/logs.cgi
You can see that some mixes have had a ton of 'hits' but the actual amount of data transferred is less than if you had 200 full downloads.