Thursday Code Puzzler: Count The Ones

It's Thursday already, so time for another code puzzler. The idea is simple: solve the coding problem as efficiently as you can, in any language or framework that you find suitable.

Note: Even though there really is nothing stopping you from finding a solution to this on the internet, try to keep honest, and come up with your own answer.  It's all about the participation!

Counting Ones

Given an array of numbers, return the occurances of the number 1 in the array. So, if the array contains 1, 2, 11, 13 you would return 4 (as 11 contains two instances of 1). 

Catch up on all our previous puzzlers here