[DEPRECATED] Quiet areas in Europe

The quietness suitability index (QSI) provides the overview with the highest (QSI=1) and lowest (QSI=0) proportion of potential quiet areas in Europe.静谧适宜性指数（quietness suitability index，QSI）用于呈现欧洲潜在静谧区域占比的极端概况，其中QSI=1对应最高占比，QSI=0对应最低占比。