There is no really up to date information on that but I came upon this article which does show some monthly figures. You can also check this site to get some figures on the traffic. These are recent findings:

Worldwide comScore numbers for July 2006:
(LINKEDIN.COM/OPENBC.COM)
Total Unique Visitors: 1,346,000 / 1,439,000
Average Daily Visitors: 75,000 / 142,000
Total Minutes: 20 million / 47 million
Total Pages Viewed : 44 million / 90 million
Average Minutes per Visitor 15.0 / 32.9
Average Pages per Visitor 33 / 63
(Figures obtained directly from comScore Europe – figures are world-wide.)
I hope this helped you....