The Hispanic population in Houston is increasing as more immigrants from Latin American countries come to work in the area. As of 2006 the city has the third-largest Hispanic population in the United States. As of 2011, the city is 44% Hispanic. As of 2011, of the city's U.S. citizens that are Hispanic, half are age 18 or older, and are therefore at the age range eligible to vote. many Hispanics in Houston are not U.S. citizens, especially those living in Gulfton and Spring Branch, and are therefore ineligible to vote in elections. As a result, Hispanics have proportionally less representation in the municipal government than other ethnic groups. As of April 2011 two of the Houston City Council members are Hispanic, making up 18% of the council. As of 2010, John B. Strait and Gang Gong, authors of "Ethnic Diversity in Houston, Texas: The Evolution of Residential Segregation in the Bayou City, 1990–2000," stated that Hispanics and Latinos had "intermediate levels of segregation" from non-Hispanic whites. As of 2006 Karl Eschbach, a University of Texas Medical Branch demographer, said that the number of illegal (undocumented) immigrants in the Houston area was estimated at about 400,000. This influx of immigrants is partially responsible for Houston having a population younger than the national average. History In the early 1980s, there were 300,000 native Hispanics, and an estimated 80,000 illegal immigrants from Mexico in Houston. In 1985, Harris County had about 500,000 Hispanics. In 1990, there were 192,220 foreign-born Hispanic residents of Houston, with 132,596, or 69%, being Mexican immigrants. 39,289 were from Central America, 12,250 were from South America, and 8,085 were from Caribbean nations. The 1990 U.S. Census said that, of the adult Houstonians who use bicycles to get to work, 32% are Hispanic. In 1997, Hispanic men tended to use bicycles more than did women. Due to Latin American social customs, Hispanic women tended to walk, or use public buses when traveling for goods or work; otherwise they stayed at home. In 1995 about 100,000 immigrants from Central America resided in Houston. As of 2001, Hispanics were almost 38% of Houston's population and 8% of the city's voting electorate. Economy In 1991, most Hispanic-owned businesses in Greater Houston were in industries with lower profit margins, such as construction, distribution, and services. The largest Hispanic-owned business was RioStar Corp., which operated Ninfa's. The business generating the highest number of sales