To quote from the UN Statistics Division’s website,
The celebration of the World Statistics Day will acknowledge the service provided by the global statistical system at national and international level, and hope to help strengthen the awareness and trust of the public in official statistics. It serves as an advocacy tool to further support the work of statisticians across different settings, cultures, and domains.
National statistics concern everyone to one degree or another. They contribute significantly to our knowledge of how well we’re doing as a country and they play a vital role in the creation of economic and social policies. The seemingly simple question "how large is a country’s labour force and what is its composition?", for example, can only be answered using data collected by a national statistical agency.
As one of the thousands of people around the world who work for the various national statistical agencies in the world, I’m proud of the role I play, however small it may be, in contributing to the better understanding of the world we live in.