In 2004 the residential population of Tres Cantos was 38,882 according to National Institute of Statistics (Instituto Nacional de Estadística, or INE) figures; however later estimates put the figure at around 45,000. Population growth has been in decline since the peak of the initial influx of residents in the early 1990s, however future plans for expansion are designed to cater for an eventual population of around 60,000. A feature of Tres Cantos' demographic profile is the large proportion of young professionals (aged 45 and under) with children, compared to Madrid and the national average. This population structure reflects the nucleus of those who left the crowded confines of Madrid to settle in the new community of Tres Cantos in the 1980s and 1990s, resulting in a predominance of young, double-income and home-owning families of 2 to 3 children. Some 40% of the town's population are under 20 (almost double the national average), and less than 6% are over the age of 65 (considerably less than half the national average). The birth rate is also double the national average. Educational accreditation among Tres Cantos inhabitants is also above the national average, with some 60% of prime income earners holding a tertiary qualification or higher. Average income levels reflect these education levels and professional employment opportunities, with over 55% having salaries in the upper-middle or higher income range. Many households have dual-incomes. Approximately 15% of households are classified as lower-middle and low-income households. An overwhelming majority of the employed work in the services sector, either in Madrid or in Tres Cantos itself. A majority of working residents regularly commute to Madrid for work, with only about a quarter of the workforce having employment in Tres Cantos itself. Those who remain behind are joined by a daily influx of approximately 20,000 who commute from Madrid and its environs to Tres Cantos for work. Light and medium industries account for some 20% of employment in Tres Cantos, the construction sector providing a further 7.4%; a bare handful (0.2%) are employed in agriculture.