The increase in postal rates came into force on 1 January 1919.
These postal rates changed frequently, and new services were added over the years.
This was the first uniform postal rate to be introduced in the world.
In addition, postal rates have risen 12 percent since January.
Companies have found themselves squeezed by more than rising postal rates.
On the darker side, the industry has been hit with huge increases in postal rates and paper costs.
The maximum impact on overall postal rates is, however, likely to be limited.
And next February we face a 20 percent increase in postal rates.
Even so, postal rates have generally remained a bit more attractive.
The April 3 increase in postal rates is expected to pull the agency out of debt by next year.