state's 2001–2011 decennial population growth rate was 13.93%, lower than the 1991–2001 growth rate of 17.8% and lower than the national rate of 17.64%. The gender ratio is 947 females per 1,000 males. As of 2011, West Bengal had a population density of making it the second-most densely populated state in India, after Bihar. The literacy rate is 77.08%, higher than the national rate of 74.04%. Data from 2010 to 2014 showed the life expectancy in the state was 70.2 years, higher than the national value of 67.9. The proportion of people living below the poverty line in 2013 was 19.98%, a decline from 31.8% a decade ago. Scheduled castes and tribes form 28.6% and 5.8% of the population, respectively, in rural areas and 19.9% and 1.5%, respectively, in urban areas. In September 2017, West Bengal achieved 100% electrification, after some remote villages in the Sunderbans became the last to be electrified. As of September 2017, of 125 towns and cities in Bengal, 76 have achieved open defecation free (ODF) status. All towns in the districts of: Nadia, North 24 Parganas, Hooghly, Bardhaman and East Medinipur are ODF zones, with Nadia becoming the first ODF district in the state in April 2015. A study conducted in three districts of West Bengal found that accessing private health services to treat illness had a catastrophic impact on households. This indicates the importance of the public provision of health services to mitigate poverty and the impact of illness on poor households. The latest Sample Registration System (SRS) statistical report shows that West Bengal has the lowest fertility rate among Indian states. West Bengal's total fertility rate was 1.6, lower than neighbouring Bihar's 3.4, which is the highest in the entire country. Bengal's TFR of 1.6 roughly equals that of Canada. Bengalis, consisting of Bengali Hindus, Bengali Muslims, Bengali Christians and a few Bengali Buddhists, comprise the majority of the population. Marwari, Maithili and Bhojpuri speakers are scattered throughout the state; various indigenous ethnic Buddhist communities such as the Sherpas, Bhutias, Lepchas, Tamangs, Yolmos and ethnic Tibetans can be found in the Darjeeling Himalayan hill region. Native Khortha speakers are found in Malda district. Surjapuri, a language considered to be a mix of Maithili and Bengali, is spoken across northern parts of the state. The Darjeeling Hills are mainly inhabited by various Gorkha communities who overwhelmingly speak Nepali (also known as Gorkhali), although there