If you have a fast connection your results will vary depending on which server the test is being carried out on, what its upstream and downstream bandwidth capacities are, how many other people are using them for testing at the time, how many hops (servers en route) between you and the server, and how much traffic is travelling between those hops at the time. Gone are the days when only data centres could transfer a lot of data in one go.
If you want to test your connection to your ISP, the best thing to do is test against a server as close to your closest internet traffic hub as possible. In the UK, servers located in data centres in London will provide the best results in terms of keeping the number of hops to a minimum. For other places, you'd have to look into your local infrastructure.