The income distribution is reported because it is used as a weighting factor for the NWI, more precisely for the private consumption expenditure (see component 2). A low Gini-Index represent a more equal , a higher value a more unequal distribution. The Index can obtain values between 0 (completely equal distribution) and 1 (one person earns all).
To obtain significant and most actual values the calculatio combines two sources of data: the results of the socio-economic panel (SOEP) conducted annually since 1984 by the German Institute for Economic Research (DIW), and the data from the micro census. The Gini-Index used here takes the arithmetic mean of the values from these two sources.