Notes:

• The first dozen or so plates (CAA through CAP) were already in circulation when the spotting started, so their dates cannot be used to calculate when they were first in distribution.
• Other unreliable dates (such as CAY and CBB) are simply due to bad record-keeping.
• Some plates (notably --G, --I, --O, --Q and --U) are never put into circulation. Presumably, they are disqualified as being too ambiguous and easily confused with other letters.
• This is a living document, and will automatically be updated with each new sighting.