To find the approximate percentage of eligible voters who voted in the 2012 city election, we can use the following formula:
\[ \text{Percentage of voters who voted} = \left( \frac{\text{Number of voters who voted}}{\text{Total number of eligible voters}} \right) \times 100 \]
In this case, 33 people voted out of 2,500 eligible voters. Plugging in the numbers:
\[ \text{Percentage of voters who voted} = \left( \frac{33}{2500} \right) \times 100 \approx 1.32% \]
So approximately 1.32% of eligible voters participated in the election.
Thus, the answer is approximately 1% when rounded to the nearest whole number.