Over here in the Netherlands the regulator claims >99.99% uptime (ie downtime slightly less than an hour per year), but I think they're being a bit modest since I can't remember a single outage in my area in the last 5 years. (Though perhaps they measure country wide in which case it might be "only" 4 nines.
The uptime is probably much better in cities than in rural areas. In Portugal, having run home servers both in a city and rural locations the difference is immense. I get more uptime out of a city server with no UPS than a rural server with a UPS that can power the server for ~30min. There are more long outages in rural areas than even transient outages in the city.
Grid is much more reliable in richer countries of Europe than it is in the States. This is one of the areas where US infrastructure is really lacking. Our power is cheap, but the reliability is bad.
The difference is mostly due to the fact that the grid in Europe tend to be mostly buried. A large part of the electrical grid in North America is aerial due to cost and geographical constraints (burying in solid rock is expensive, and doesn't make sense with lower population densities), which makes it much more vulnerable to damage by storms.
