There is no annualized standard deviation, however, all matlab processes can be used only on parts of your data, so you could manually limit for std deviation calculation to only account for year 1, year 2 etc.
You did not specify how your data is stored, so I'm going to assume that it is a vector.
data =
1
2
3
4
5
6
Say 1 to 3 is year 1, 4 to 6 is year 2.
std_year1 = std(data(1:3,:)
The correct syntax is: data(rows, columns) where a single colon simply means all.
