The question is not entirely clear, nor can you easily find such numbers. You'd need to find the number of players, and multiply it by the average playtime per day, as an example. But I am not aware of any way (short of Blizzard supplying the info) of finding out what the average time played per day is.
a little over 137,000
It is rather impossible to calculate how many hours the whole entirety of the human race has spent playing World of Warcraft and its expansions. It is impossible because you would have to have a log of each and every persons playing time, since the game started, and there has been over 11 million (at one time) playing the game.
To see how long you have played a character, type /played. There is no way to see how long someone on another account has been playing with out an addon, and then you both would have to have the addon.
Currently in Mists of Pandaria, the latest expansion to World of Warcraft, there are 90 levels.
There are roughly 9-10 million active subscriptions for World of Warcraft.
Assuming every single subscriber in World Of Warcraft plays which is ten million subscribers, then it is assumed that there are ten million people playing world of Warcraft.
The most popular war game online is World of Warcraft. World of Warcraft has been played extensively by many people since 2004 and continues to be one of the most popular games to date.
It is estimated that around 9500 people join World of Warcraft every day.
too many...
There are many forums available on the official World of Warcraft website. WoW also has many "fansites" that can be found on the official website: http://www.worldofwarcraft.com Here is another website: http://www.fanaticsofwow.webs.com
In the past couple of years, there has been about 800,000 subscriptions canceled. This leaves World of Warcraft with about 10.2 million subscribers.
World of Warcraft had approximatly 9.3 million subscribers by the end of 2007. In January (2007) they had about 8 million.