The following table shows the numbers of chairs made of plastic and of steel in 5 different colours that were sold from a furniture showroom during a sale.
| Colour | Steel | Plastic |
| C1 | 10 | 12 |
| C2 | 12 | 6 |
| C3 | 8 | 14 |
| C4 | 6 | 18 |
| C5 | 9 | 11 |
The total number of chairs of colour C3 sold are what percentage of all the chairs of these 5 colours sold, both plastic and steel ones put together? [Give your answer correct to 2 decimal places.]