As there is currently no data available on device reliability a 3% failure rate has been assumed for years 1-3 and 10% has been assumed for year 4 onwards.
Gan nad oes data ar gael ar hyn o bryd ar ddibynadwyedd dyfeisiau, tybiwyd cyfradd fethiant o 3% ar gyfer blynyddoedd 1-3 a thybiwyd 10% ar gyfer blwyddyn 4 ymlaen.