Although Kenya is the biggest and most advanced economy in east and central Africa, and has an affluent urban minority, it has a Human Development Index (HDI) of 0.519, ranked 145 out of 186 in the world. As of 2005, 17.7% of Kenyans lived on less than $1.25 a day. The important agricultural sector is one of the least developed and largely inefficient, employing 75% of the workforce compared to less than 3% in the food secure developed countries. Kenya is usually classified as a frontier market or occasionally an emerging market, but it is not one of the least developed countries.