How much of this is caused by marketing mailing lists sending messages to people who never subscribed?

I know I get a fair amount of unsolicited marketing list messages that do have an Unsubscribe link, which I click, but I also mark as spam because I never subscribed to it in the first place (of course, I'm also not using Google Mail, I'm using FastMail with a personalized SpamAssassin filter, but I assume it will still influence the global default SpamAssassin filter).