------
## 最终结论
```python
def positive_count(arr):
    positive_count = sum(1 for x in arr if x > 0)
    return round(positive_count / len(arr), 2)

# Test cases
assert positive_count([0, 1, 2, -1, -5, 6, 0, -3, -2, 3, 4, 6, 8]) == 0.54
assert positive_count([2, 1, 2, -1, -5, 6, 4, -3, -2, 3, 4, 6, 8]) == 0.69
assert positive_count([2, 4, -6, -9, 11, -12, 14, -5, 17]) == 0.56
```