The time series in 1/3  BIS central bankers' speeches  the World Inequality Database are the result of an ingenious combination of various data sources, including survey data, tax data and, sometimes, information from named lists of wealthy individuals to improve estimates of the very top of the wealth distribution.
Excessive liabilities, even if supported by the market, imply a transfer of wealth from future generations to the current ones – a move that is decided unilaterally by the current generation. Seen from this perspective, fiscal constraints on governments do not appear as a loss of sovereignty but rather as the condition for preserving this very sovereignty over time.