Across the whole Earth, about 70% of the surface is water and 30% is land.
What I want, though, is to restrict the scope to the northern hemisphere (NH) only. What percentage of NH surface is land?
It would also be good to clarify exactly how we define "land". If I'm not mistaken, the 70/30 split of water/land actually places inland rivers and lakes as land area.
Please also cite a source for this. The only google result I found with an answer was yahoo questions.