------
## 最终结论
```python
def zero_count(arr):
    zero_count = 0
    for num in arr:
        if num == 0:
            zero_count += 1
    total_length = len(arr)
    return zero_count / total_length

# Test cases
assert zero_count([0, 1, 2, -1, -5, 6, 0, -3, -2, 3, 4, 6, 8]) == 0.15
assert zero_count([2, 1, 2, -1, -5, 6, 4, -3, -2, 3, 4, 6, 8]) == 0.00
assert zero_count([2, 4, -6, -9, 11, -12, 14, -5, 17]) == 0.00
```