Step 1: Use percentage increase formula
\[
\text{Percentage increase} = \left( \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \right) \times 100
\]
Step 2: Substitute values
\[
= \left( \frac{581 - 560}{560} \right) \times 100
\]
\[
= \left( \frac{21}{560} \right) \times 100
\]
\[
= 3.75%
\]
Thus, the correct answer is 3.75%.