Here are graphs from the number of players world wide. The players have been divided by game types. The vast majority of players are playing Counter-Strike 1.6.
During a day the total number of players fluctuates between 60 000 and 120 000 players. The fluctuation is caused by players going to sleep and waking up. The graph is smoothed by the fact that players are from all around the world, so not everybody go to sleep at the same time. Quite often it can be seen, when there are major sports events, that the graph goes up and down because players consider TV sports better than virtual.
The graphs are updating live.
Here is the same graph for one year period. It is visible that number of players is growing. It happens because there are more servers and more game types. Time goes on and everybody keep playing, so that makes the numbers grow.
This is nice way to see which way the trends are going. Who would have believed Counter-Strike 1.6 is still the killer game.