Sales of George R.R. Martin's Song of Ice and Fire series have passed 58 million, according to The Guardian.
In an article on how the commercial and critical success of the series has impacted the global fantasy market, The Guardian talks to George's publishers and some of his colleagues and friends, including Joe Abercrombie and sometimes-collaborator Lisa Tuttle.
Before 2011, when the TV series Game of Thrones began, sales of ASoIaF were estimated at roughly 5 million copies. In the year 2011-12, the series sold 9 million copies by itself and it would appear that sales have continued to increase at a formidable rate. Martin's total sales have exceeded the likes of Terry Brooks and are closing in on Robert Jordan and Terry Pratchett (authors with many more published novels) very quickly. It's no wonder that Martin's publishers are eager to get their hands on The Winds of Winter, the sixth (and hopefully penultimate) novel in the series.
Given that A Dance with Dragons dominated the bestseller lists in 2011 at a time when sales of the overall series were far lower, it's very likely that Winds will be the biggest-selling novel of the year if it does make it out in 2016 (as Martin recently revealed was his target).