How often to WAN links break due to network hardware failure or
physical line failure?  For example, new construction digs through the
fiber, or the Central Office router overheats and stops.  I'm
interested in point-to-point failure, so if an ISP has redundant links
that failover transparent to me, I'm not counting this.  Answer would
be in the form of outages/year at an average of seconds/outage.  I'd
also like at least one source that I can reference as my source.  Two
or three would be great.
Thanks!
Karen