Bhutan’s population at 2,049,412 in 2001. However, the official 1990 estimate by the Bhutanese government gave the country’s population as about 600,000. The discrepancy is due to the fact that, beginning in 1990, the official census has excluded people of Nepali origin. Using either estimate, Bhutan’s population density is low. Based on the 2001 estimate, the country has 44 persons per sq km (113 per sq mi). The annual growth rate is estimated at 2.2 percent. The population is dispersed widely. Large tracts are virtually empty; others are relatively crowded. The Middle Himalayan valleys contain nearly half of the nation’s population, concentrated in the middle portion of the Wong, Sankosh, and Manas river valleys and in the valleys of their tributaries. The southern zone, close to the Indian border.