Dave Taylor's article is a good follow up to my comments about the importance of supporting Christian missions which go where no Christian has gone before.
After categorising the globe into World A (unevangelized; e.g., Turkey, Iran, Niger), World B (evangelized non-Christian; e.g., Indonesia, India, Chad) and World C (Christian; e.g., US, UK, Kenya, Ukraine), Dave provides us with some sobering statistics from The World Christian Encyclopedia and World Christian Trends.
91% of Christian literature is consumed by, and 96% of all Christian radio and TV programming is aimed at, World C countries. Just 0.1% of Christian literature and radio/TV programming reaches World A countries.
"91% of all Christian outreach/evangelism does not target non-Christians but targets other Christians in World C countries, cities, peoples, populations, or situations." In other words, for every worker in an unreached area, there are nine trying to reach nominal Christians, the backslidden or those who already have access to Christian ministry in some form.