Rattlesnakes

I read the following in answer to another persons question: "Up to 4 individuals from each species of herp (including rattlesnakes) may be taken and possessed (dead or alive) with a hunting license. They can be kept as pets or killed for hat band or other personal uses. Specific to rattlesnakes: Up to 6 rattlesnake skins may be sold/bartered (new). The take and possession limit of 4 still applies, so catch 4, sell the skins and catch 2 more to sell. The rattlesnake skins can only be sold not the entire animal---no meat may be sold, consistant with other F&G rules. No live rattlesnakes may be sold, except with a Commercial permit from Fish and Game. Keeping rattlesnakes alive, requires special cage requirements, glass containers or double screens to prevent fangs from reaching outside cage. If you have other questions, please call your local Fish and Game office." My Question is what is the time length for this? For instance say I killed 4 rattlesnakes, ate the meat and sold the skins in 2012. I then caught 2 more within 2012 and did the same thing (total of 6). In 2013 will I be able to do this again or is the limit of 6 per lifetime, not per year?