Agnostics celebrate any and every holiday that they choose to celebrate, but they probably don't celebrate religious holidays for the same reasons that believers do. For example, many agnostics celebrate Christmas, just because it is a major secular holiday (as well as a religious one). What prevents an agnostic from celebrating Thanksgiving? It is a wonderful holiday.
That's it. Take the religious celebrations and remove the god stuff. That's what we celebrate. Some of us pick and choose holidays, or choose to celebrate none; there are no set rules. Atheism is not a creed or formal practice.
Agnostics are not a monolithic bloc of people. They all have different ideas about how to do things and what to celebrate.
However, they usually follow the trends on the society they live within. Most would celebrate birthdays.
It's all up to the individual, but most people celebrate SOMETHING.
Take Christmas as one example. Many agnostics observe Christmas, or Midwinter, or Yule, or whatever they choose to call it. Christians are supposed to believe in the deity of Jesus, and emphasize his birth when observing Christmas. Agnostics may consider the existence of God a possibility, not a forgone conclusion; and if God exists, Jesus may or may not be the humanization of God. However, Midwinter was already being celebrated (sometimes for 12 days) before anybody connected it to the birth of Jesus. In fact, there is no real evidence that Jesus was even born in December.
The spring celebration that became Easter also has been around longer than Christianity.
And, of course, there are celebartions that have nothing to do wityh religion, such as July 4 Independence Day in the USA, September 16 Dia del Grito in Mexico, and so forth. there is no reason for an agnostic not to celebrate those, or whatever applies to his own country.
Agnostics by their nature dont believe in anything as they feel they are not equiped to understand reality./
Agnostics do not believe anything about God. Agnostics do not believe in any type of religion.
There is no recognized 'leader' for agnostics. However, a fair number agnostics are also interested in secular reasoning and philosophy, so many of the great philosophers of the ages (Socrates, Hume, Kant, Descartes) are read and debated by some agnostics. There are also a number of vocal agnostics/atheists who are in the public limelight a great deal, including Richard Dawkins.
All countries.
31.4%
That isn't a simple question to answer. Not all agnostics necessarily believe the same things. So, some do, some don't.
You seem to be lumping all agnostics together into one uniform mindset. The reality is that agnostics, like in almost any group of people, all have their own separate thoughts and opinions. So I'm afraid that your question really doesn't have much of an answer.
They can be either Atheists or Agnostics.
agnostics
The Boy Scouts of America's official position is that atheists and agnostics cannot participate as Scouts or adult Scout Leaders in its traditional Scouting programs. - Wikipedia
There is not really a history of agnostics. Agnosticism is a Greek word meaning "without knowledge". Agnostics do not feel like there is enough evidence, one way or another, to prove or disprove the existence of a god and other supernatural phenomena. There have been agnostic views for as long as atheistic views, and religious beliefs have been around.
There is no reason to expect all agnostics to have the same answer to that. Obviously the world came to exist some way. If you believe you can explain exactly how and why, then your answer works for you. Your answer might not satisfy everyone.