To find out the concentration of \(SO_2\) in the air (in parts per million, i.e., ppm), the data was collected for \(30\) localities in a certain city and is presented below:
| Concentration of \(SO_2\) (in ppm) | Frequency |
| \(0.00-0.04\) | 4 |
| \(0.04-0.08\) | 9 |
| \(0.08-0.12\) | 9 |
| \(0.12-0.16\) | 2 |
| \(0.16-0.20\) | 4 |
| \(20-0.24\) | 2 |
Determine the mean concentration of \(SO_2\) in the air.
Mean \(=\) ppm
[Note: Round off the answer to three decimal places and enter the answer]