It probably varied widely based on locale. I did tech support for a Northern California ISP in 1999, and there were plenty of people connecting at 53k, even co

It probably varied widely based on locale. I did tech support for a Northern California ISP in 1999, and there were plenty of people connecting at 53k, even considering that we were seeing people who were calling because of problems. 48k and 44k were also very common speeds to connect to at that time, but really whether you could connect close to the full speed depended quite a bit on the wiring in your house, from your house to and central office, and also the weather (rainy days resulting in staticy sounding lines for many people, and quite an increase in tech support calls). I also remember a fairly amazing story about how a user (which I never spoke to, but others had) finally diagnosed their own problem where their 1.5 Mbps ADSL connection would have a problem at approximately the same time each evening as when the street lamp turned on. Those old Alcatel 1000 DSL modems had notoriously bad problems with interference.