The reason is the important increase of the Swiss Franc against de US
Dollar.

Many modern postage issues, beginning with stamps released in the mid-1960s,
were increased to approx. double face value or a bit more for popular
topical sets and some SS.

Other increases are for Thailand and Uzbekistan (due to limited quantities
for the later).

Source: Linn's Stamp News, Sept. 19, 2011.

--
Victor Manta, PWO, AIJP

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