A new problem - A staircase

My new house has a staircase with 12 steps. I can go down the steps one at a time or two at a time.
For example, I could go down 1 step, then 1 step, then 2 steps, then 2, then 2,1,1,1,1.
In how many different ways can I go down the 12 steps, taking one or two steps at a time?