What wrong with this picture?

The Hot Water Heater Anode on the left is brand new and the one on the right has about 1 year of full timing use on it.  I finally got around to checking the anode and as you can see the anode is totally gone, nothing left.

What does the anode rod do?  Well the purpose of the anode rod is to control corrosion. The magnesium anode rod protects the tank by corroding in place of the steel tank. Because the rod is designed to corrode, it will eventually wear away. After this happens, corrosion of the steel accelerates. So it is very important to replace it long before it gets like the one in this picture.    From now on I will be checking this about every 3 months.  From what I have found out the anode should be replaced when it is about 70% worn away.  The bottom line is replace the $12.00 anode on a regular basis or replace the $400.00 to $500.00 Hot Water Heater because it failed prematurely.