how good is the data reliability with CD ROM and DVD RAM?

Below is a sampling of disks recorded between 2001 and 2009. It is likely that the disks of the same type were from the same package because I don't use many disks. They were stored without much care, but in a spaces tolerable to humans for reasonable periods. Imation CD-R recorded 2003/12/29 readable Imation CD-R recorded 2004/01/02 recoverable errors Imation CR-R recorded 2001/12/18 recoverable errors Imation CD-R recorded 2005/07/15 recoverable errors Imation CD-R recorded 2001/12/24 recoverable errors TDK DVD-R recorded 2006/02/05 recoverable errors TDK DVD-R recorded 2009/09 unrecoverable errors. The edges of the disk have a strange faded coloration. TDK DVD-R recorded 2007/10/07 readable Memorex CD-R recorded 2005 unrecoverable errors