8766 hrs/yr (assuming 365.25 days/year) * 90% uptime: Down 876.6 hours, or 36.525 days. 3 days per month. * 99% uptime: 87.66 hours, or 3.65 days. * 99.9% uptime: 8.77 hours * 99.99% uptime: 0.877 hours, or 52.6 minutes * 99.999% (5 nine's!) uptime: 0.0877 hours, or 5.26 minutes * 99.9999% uptime: 0.0088 hours, or 0.526 min, or 31.56 seconds * 99.99999% uptime: 0.0526 min, or ~3 seconds * 99.999999% uptime: ~1/3 second outage per year