The following table shows the number of trains that originate in the five different zones of the railway network of a country.
| Zone | Trains |
| Z1 | 690 |
| Z2 | 710 |
| Z3 | 830 |
| Z4 | 670 |
| Z5 | 900 |
The total number of trains that originate in Z3 and Z4 taken together is what percentage of the total number of trains that originate in all the 5 zones taken together?