According to their website, there are 6,697 unreached people groups, making up 42.2% of all people groups. They define unreached as "a people group among which there is no indigenous community of believing Christians with adequate numbers and resources to evangelize this people group."
Now read the following statistics at Nigel Barham's blog (emphasis added):
According to missionfrontiers.org, Christians give about 1.7% ($213B) of their income to Christian causes (like their church). Of that 1.7%, only 5.4% ($11.4B) is given to foreign missions. (Amazing: the *entire* annual global missions budget funding 250,000 missionaries is just 1/4 of Bill Gates' fortune!) Of that 5.4%, 87% goes to missions among Christians, 12% goes for work among already evangelized non-Christians, and only 1% goes for work among the unreached or unevangelized people of the world. That means that just 5.4% of 1.7% (0.0918%) of Christians' money goes to missions, and that just 1% of *that* (0.000918%) goes to missions among the unreached.