45% VP's for solo
65% VP's for coalition/teams.

depends on the games you are playing....
If you play a 22 person game, and you join an alliance, in theory you should have 3/22 = 13.6% chance of winning.
If you play that same game, but go for a solo victory, then you have a 1/22 chance of winning (4.5%).

If you are playing a game that starts with 100 people in it...and it doesn't allow people to join in an alliance...then in theory, you only have a 1% chance of winning that game.

In reality, however, many players go inactive very quickly in most games, so your odds of winning go up a lot if you have a bunch of people that go inactive.

if you are playing "clash of nations", there are 22 players in that game.
if you join a coalition (which has 3 countries in the coalition), you should win 3 out of every 22 games...which is about 1 in every 7 games.

So if you play 8 games, then you should win a little bit more than 1 game.

But none of that accounts for how good a player you are or how good the competition is...
If you play 8 games and you are a really good player, you might win 4-5 of those games (or more).
If you are an average player, and a lot of the players are brand new and/or a bunch of players quit after a couple of days, then you can easily win 3-4 out of 8 games, not because you are a good player, but because the competition is bad or quits.

Depends on the player. Awerage players should get 1 in 20 in small maps or 1 in 50 on big ones