It really depends on which mail account you are talking. On my hotmail one, since it's the oldest I have, I must get about 10 or so spam in the Inbox per week (of course, the Spambox is always filled with TONS of garbage)
I have another account at argentina.com, which rarely gets any spam, usually about 2 per week (Spambox here doesnt get that many messages either)
And the newest one I have, at Gmail, which I have since around 5 months, I think I have only gotten 1 spammy post at all. Kinda like I was expecting that, since I heard Gmail is probably the best mail service.