ocr: Required Availability Times 916.hours 20% 21 hours 50% 17-23hours 23% Source l Storce € This chart from 1999 DARTS snows the pere cent: of applications by the nours: per day the mission-chtical application needs: to be avail- able. Today, 50% of the applications regure nonstop avaiability: IR 1991 this numper was less than 6%.