NIS firewall: showing a huge amount of bocked connection attempts

hello,

since i installed NIS for mac a few months ago, it's always been showing a huge number for "connection attempts blocked" (usually above 15,000) on the firewall statistics window. i was just wondering if that's normal to happen? Is it something i should be worrying about? 

 thank you very much in advance

p.s. a screenshot picture of the firewall history was attached in private
Screen Shot 2012-01-10 at 20.46.46.png