Naming is in sequence alphabetically and there is a release every 6 months. Maverick Meerkat was released recently. A B C D E F G H I J K L M... so that means... (13-6 releases) * (6 months/1 release) * (1 year/12 months) = 3.5 years
Except that there was no A, B, or C release in the current lineup, because it started with Warty Warthog, Hoary Hedgehog, Breezy Badger, and then they decided on the sequentially named releases starting with Dapper Drake (6.06).