Rocketing oil prices will make 2008 the year of natural gas, as it is likely to outperform both petroleum and oil, Jim Cramer told viewers of his "Mad Money" TV show Thursday. "It's a clean, clean commodity whose time has now come," Cramer said. And the perfect stock to play the natural gas market is Ultra Petroleum ( UPL), said Cramer. The stock is up more than 24% since he recommended it on July 9, but there's even more upside. Ultra Petroleum is focused on production growth, Cramer said. On Friday, the company raised its production guidance for 2007 by a "staggering" 12.1%. The company's production in 2007 is expected to be 33% higher than what it was in 2006.