Despite their flaws, one thing I love about my ISP is that they openly publish the utilization MRTG graphs for their local fiber connection nodes.
So you can see where I live, they're starting to get close to saturation http://qos.plala.or.jp/traffic/flets/kagoshima.html but in other parts of the country they've already started to peak out http://qos.plala.or.jp/traffic/flets/chiba.html