Nobody's heard of Opera. It's just the awkward fifth wheel in the browser ballot. IE is the Windows-fascism browser, Safari is the Apple-fascism browser, and firefox and chrome are actually good web browsers. Just because people are given the option of choosing Opera doesn't mean they're going to. Same with Netscape. It's like asking somebody if they'd prefer "X brand beer" when presented with "store brand 1", "store brand 2", "Y brand beer", "smooth lager" and "awesome lager".
[guess which browser were which beers in that metaphor...oh and for people who know their beer:
It's like asking somebody if they'd prefer "Milwakee's best" when presented with "Coors Light", "Bud Light", "Natty Light", "Hoegaarden" and "Sam Adams".]