prime time; these quotas indicate at least half of Canadian prime-time programs must be Canadian in origin, but the majority of this is served by national and local news or localized entertainment gossip shows such as Global Television Network's Entertainment Tonight Canada and CTV Television Network's ETalk. Likewise, the vast majority of Spanish-language programming in North America comes from Mexico. Televisa, a Mexican network, provides the majority of programming to the dominant U.S.-based Spanish broadcaster, Univision. Univision does produce a fairly large amount of unscripted Spanish-language programming, the best known having been the long-running variety show Sábado Gigante, hosted and created by Chilean national Don Francisco. Univision's distant second-place competitor, Telemundo, produces a much greater share of in-house content, including a long line of telenovelas. In Quebec, the largest Francophone area of North America, French-language programming consists of originally produced programs (most of which are produced in Montreal, with a few produced in Quebec City) and a few French-language dubs of English language programs. On all of the Quebec networks, entertainment programming is scheduled only between 8 and 10p.m., with the 10–11p.m. hour given over to a network newscast or a nightly talk show. United States Prime time is the dayparting (a block of a day's programming schedule) with the most viewers and is generally where television networks and local stations reap much of their advertising revenues. In recent years, television advertising expenditure in the US has been highest during prime-time drama shows. The Nielsen ratings system is explicitly designed for the optimum measurement of audience viewership by dayparts with prime time being of most interest. Television viewership is, in general, highest on weekday evenings, as most Americans are working time, asleep during the overnights, and out taking part in social events on weekends; thus, television has its highest audience at times when people are unlikely to be away from home. Prime time for radio is called drive time and, in Eastern and Pacific Time, is 6–10a.m. and 3–7p.m. and, for Mountain and Central Time, is 5–9a.m. and 2–6p.m. The difference between peak radio listenership and television viewership times is due to the fact that people listen to their radios most often while driving to and from work (hence the name "drive time"). A survey by Nielsen revealed that viewers watched almost two hours' worth of TV during prime time. Mexico In Mexico, central time normally starts at 7:30 p.m.