If I remove facebook from social networking site then how much twitter occupy ?

I agree. Faceboke is way better then twitter when it comes to traffic source. Although having both is the best, because some people prefer facebook, other twitter. 

I actually have mostly real followers on Twitter as far as I know. I don't think they are mostly bots at all. It's just that some real people schedule blog posts to be posted on Twitter throughout the day. As long as it is informative content I don't think there should be anything wrong with this. 

The people above who answered this may be right though. Facebook may bring you real traffic, even if it may be a smaller amount of followers. Still, FB is not a stranger to spam either. I just happen to like Twitter because it helps me gain followers quickly. I had a fair amount of traffic from it-probably more than from FB.