Unity Coroutine Yields but also continues to update variables

Question

I'm looking for this coroutine to update a variable every second:

int i = 0;

void Start()
{
    StartCoroutine ("MyCoRoutine");
}

IEnumerator MyCoRoutine()
{
    while ( true )
    {
        print ("Counter Value: " + i++);
        yield return new WaitForSeconds(1f);
    }
}

I would expect the console debug to show an incrementing value every second, instead, it does update every second but with non-consecutive values:

Counter Value: 0 UnityEngine.MonoBehaviour:print(Object) c__Iterator0:MoveNext() (at Assets/building.cs:81)

Counter Value: 51 UnityEngine.MonoBehaviour:print(Object) c__Iterator0:MoveNext() (at Assets/building.cs:81)

Counter Value: 119 UnityEngine.MonoBehaviour:print(Object) c__Iterator0:MoveNext() (at Assets/building.cs:81)

etc..

What am I not understanding about coroutines/yield that would cause such a strange phenomena?