Question: What is the approximate Romani population of the country that has the rapid transit system that Roma station is a part of?

full_context: Document 1: Campo Grande (Lisbon Metro): Campo Grande is an elevated interchange station on the Yellow and Green Lines of the Lisbon Metro. It has a large bus terminal at ground level and is located on Rua Cipriano Dourado just north of Avenida General Norton de Matos in the Lisbon parish of Campo Grande.
Document 2: Portugal: In 2007, Portugal had 10,617,575 inhabitants of whom about 332,137 were legal immigrants. In 2015, Portugal had 10,341,330 inhabitants of whom about 383,759 were legal migrants, making up 3.7% of the population. In 2017, Portugal had 416,682 legal residents of foreign origin, of which 203,753 identified as male, and 212,929 as female.Portugal's colonial history has long since been a cornerstone of its national identity, as has its geographic position at the south-western corner of Europe, looking out into the Atlantic Ocean. It was one of the last western colonial European powers to give up its overseas territories (among them Angola and Mozambique in 1975), turning over the administration of Macau to the People's Republic of China at the end of 1999. Consequently, it has both influenced and been influenced by cultures from former colonies or dependencies, resulting in immigration from these former territories for both economic and personal reasons. Portugal, long a country of emigration (the vast majority of Brazilians have Portuguese ancestry), has now become a country of net immigration, and not just from the last Indian (Portuguese until 1961), African (Portuguese until 1975), and Far East Asian (Portuguese until 1999) overseas territories. An estimated 800,000 Portuguese returned to Portugal as the country's African possessions gained independence in 1975.Since the 1990s, along with a boom in construction, several new waves of Ukrainian, Brazilian, Lusophone Africans and other Africans have settled in the country. Romanian, Moldovans, Kosovar and Chinese have also migrated to the country. Portugal's Romani population is estimated to be at about 40,000. Numbers of Venezuelan, Pakistani and Indian migrants are also significant.
Document 3: List of metro systems: This list of metro systems includes electrified rapid transit train systems worldwide. In some cases, metro systems are referred to as subways, U-Bahns or undergrounds. As of October 2014, 157 cities in 55 countries around the world host the approximately 160 metro systems that are listed here. The London Underground first opened as an ``underground railway ''in 1863 and its first electrified underground line opened in 1890, making it the world's first metro system. The metro system with the longest route length is the Shanghai Metro; the busiest one is the Beijing Subway; and the one with the most stations is the New York City Subway.
Document 4: Cabo Ruivo (Lisbon Metro): Cabo Ruivo is a station on the Red Line of the Lisbon Metro. The station is located on Av. Padua, near the intersection with Av. Infante Dom Henrique serving the Cabo Ruivo area of the city.
Document 5: Guinea-Bissau: Portuguese natives comprise a very small percentage of Guinea-Bissauans. After Guinea-Bissau gained independence, most of the Portuguese nationals left the country. The country has a tiny Chinese population. These include traders and merchants of mixed Portuguese and Chinese ancestry from Macau, a former Asian Portuguese colony.
Document 6: Colli Albani (Rome Metro): Colli Albani is a station on the Rome Metro. It is on Line A and is located in Largo dei Colli Albani, between the Furio Camillo and Arco di Travertino stations.
Document 7: Portugal: By the early 1970s Portugal's fast economic growth with increasing consumption and purchase of new automobiles set the priority for improvements in transportation. Again in the 1990s, after joining the European Economic Community, the country built many new motorways. Today, the country has a 68,732 km (42,708 mi) road network, of which almost 3,000 km (1,864 mi) are part of system of 44 motorways. Opened in 1944, the first motorway (which linked Lisbon to the National Stadium) was an innovative project that made Portugal among one of the first countries in the world to establish a motorway (this roadway eventually became the Lisbon-Cascais highway, or A5). But, although a few other tracts were created (around 1960 and 1970), it was only after the beginning of the 1980s that large-scale motorway construction was implemented. In 1972, Brisa, the highway concessionaire, was founded to handle the management of many of the regions motorways. On many highways, toll needs to be paid, see Via Verde. Vasco da Gama bridge is the longest bridge in Europe.
Document 8: Portugal: The early history of Portugal is shared with the rest of the Iberian Peninsula located in South Western Europe. The name of Portugal derives from the joined Romano-Celtic name Portus Cale. The region was settled by Pre-Celts and Celts, giving origin to peoples like the Gallaeci, Lusitanians, Celtici and Cynetes, visited by Phoenicians and Carthaginians, incorporated in the Roman Republic dominions as Lusitania and part of Gallaecia, after 45 BC until 298 AD, settled again by Suebi, Buri, and Visigoths, and conquered by Moors. Other influences include some 5th-century vestiges of Alan settlement, which were found in Alenquer (old Germanic Alankerk, from Alan+kerk; meaning church of the Alan (people), Coimbra and Lisbon.
Document 9: Portugal: Portugal lost much of its wealth and status with the destruction of Lisbon in a 1755 earthquake, occupation during the Napoleonic Wars, and the independence of Brazil, its wealthiest colony, in 1822. After the 1910 revolution deposed the monarchy, the democratic but unstable Portuguese First Republic was established, later being superseded by the "Estado Novo" right-wing authoritarian regime. Democracy was restored after the Portuguese Colonial War and the Carnation Revolution in 1974. Shortly after, independence was granted to all its colonies, with the exception of Macau, which was handed over to China in 1999. This marked the end of the longest-lived European colonial empire, leaving a profound cultural and architectural influence across the globe and a legacy of over 250 million Portuguese speakers today.
Document 10: Portugal: The two largest metropolitan areas have subway systems: Lisbon Metro and Metro Sul do Tejo in the Lisbon Metropolitan Area and Porto Metro in the Porto Metropolitan Area, each with more than 35 km (22 mi) of lines. In Portugal, Lisbon tram services have been supplied by the Companhia de Carris de Ferro de Lisboa (Carris), for over a century. In Porto, a tram network, of which only a tourist line on the shores of the Douro remain, began construction on 12 September 1895 (a first for the Iberian Peninsula). All major cities and towns have their own local urban transport network, as well as taxi services.
Document 11: Lisbon Metro: The Lisbon Metro () is the rapid transit system of Lisbon, Portugal. Opened in December 1959, it was the first subway system in Portugal.
Document 12: Roma (Lisbon Metro): Roma is a station on the Green Line of the Lisbon Metro. The station is located on Avenida de Roma, near the intersection with Av. dos Estados Unidos da América, enabling access to the Roma-Areeiro railway station nearby.
Document 13: Spagna (Rome Metro): Spagna is an underground station on Line A of the Rome Metro, which was inaugurated in 1980. It is situated in the rione Campo Marzio and is named after the nearby Piazza di Spagna.
Document 14: El Metropolitano: El Metropolitano is a new Bus rapid transit system serving the city of Lima, Peru. Its construction began in the year 2006 during Luis Castañeda Lossio's period as Mayor of Lima.
Document 15: Portugal: The Portuguese language is derived from the Latin spoken by the romanized Pre-Roman peoples of the Iberian Peninsula around 2000 years ago—particularly the Celts, Tartessians, Lusitanians and Iberians. In the 15th and 16th centuries, the language spread worldwide as Portugal established a colonial and commercial empire between 1415 and 1999. Portuguese is now spoken as a native language in five different continents, with Brazil accounting for the largest number of native Portuguese speakers of any country (200 million speakers in 2012).
ground_truth: 40,000
sub_queries: Roma >> part of Answer: Lisbon Metro
Lisbon Metro >> country Answer: Portugal
What is the approximate Romani population in Portugal ? Answer: 40,000