has issued stamps with the same posthorn motif for over a century, changing only the details from time to time as printing technology improves, while the US has placed the flag of the United States into a wide variety of settings since first using it on a stamp in the 1950s. While numeral designs are eminently practical, in that they emphasize the most important element of the stamp, they are the exception rather than the rule. By far the greatest variety of stamp design seen today is in pictorial issues. The choice of image is nearly unlimited, ranging from plants and animals, to figures from history, to landscapes, to original artwork. Images may represent real-world objects, or be allegories or abstract designs. The choice of pictorial designs is governed by a combination of anniversaries, required annual issues (such as Christmas stamps), postal rate changes, exhaustion of existing stamp stocks, and popular demand. Since postal administrations are either a branch of government or an official monopoly under governmental supervision, the government has ultimate control over the choice of designs. This means that the designs tend to depict a country as the government would like it to be perceived, rather than as it really is. The Soviet Union issued thousands of stamps extolling the successes of communism, even as it was falling apart, while in the US the only contemporary stamp hinting at the unrest of the 1960s is an issue exhorting Americans to support their local police. In some cases, overt political pressure has resulted in a backlash; a famous example is that of the US in the late 1940s, when the US Congress had direct authority over stamp design, and a large number of issues were put out merely to please a representative's constituency or industry lobbyists. The resulting uproar resulted in the formation of an independent Citizens' Stamp Advisory Committee that reviews and chooses from hundreds of proposals received each year. Occasionally the public is polled for its choice of design, as with the US Elvis stamp of 1993, or some issues of the Celebrate the Century series. Many countries have specific rules governing the choice of designs or design elements. Stamps of the UK must depict the sovereign (typically as a silhouette), while stamps of the US may not visibly depict any person who has been dead for less than 10 years, except for ex-Presidents, who may appear