number of euros to fix an exchange rate at 1.00 EUR = 1.20 CHF, to protect its trade. This action temporarily eliminated the franc's hard currency advantage over the euro but was abandoned in January 2015. Demand Investors as well as ordinary people generally prefer hard currencies to soft currencies at times of increased inflation (or, more precisely, times of increased inflation differentials between countries), at times of heightened political or military risk, or when they feel that one or more government-imposed exchange rates are unrealistic. There may be regulatory reasons for preferring to invest outside one's home currency, e.g. the local currency may be subject to capital controls which makes it difficult to spend it outside the host nation. For example, during the Cold War, the rouble in the Soviet Union was not a hard currency because it could not be easily spent outside the Soviet Union and because the exchange rates were fixed at artificially high levels for persons with hard currency, such as Western tourists. (The Soviet government also imposed severe limits on how many roubles could be exchanged by Soviet citizens for hard currencies.) After the fall of the Soviet Union in December 1991, the rouble depreciated rapidly, while the purchasing power of the US dollar was more stable, making it a harder currency than the rouble. A tourist could get 200 roubles per US dollar in June 1992, and 500 roubles per dollar in November 1992. In some economies, which may be either planned economies or market economies using a soft currency, there are special stores that accept only hard currency. Examples have included Tuzex stores in the former Czechoslovakia, Intershops in East Germany, Pewex in Poland, or Friendship stores in China in the early 1990s. These stores offer a wider variety of goods many of which are scarce or imported than standard stores. Mixed currencies Because hard currencies may be subject to legal restrictions, the desire for transactions in hard currency may lead to a black market. In some cases, a central bank may attempt to increase confidence in the local currency by pegging it against a hard currency, as is this case with the Hong Kong dollar or the Bosnia and Herzegovina convertible mark. This may lead to problems if economic conditions force the government to break the currency peg (and either appreciate or depreciate sharply) as occurred in the 1998–2002 Argentine great