This paper includes supplementary material for the paper [A.N. Gorban, A.
Zinovyev, Principal manifolds and graphs in practice: from molecular biology to
dynamical systems, International Journal of Neural Systems 20 (3) (2010),
219-232. E-print: arXiv:1001.1122 [cs.NE]]. We present details of the analysis
of the nonlinear quality of life index for 162 countries. This index is based
on four indicators: GDP per capita, Life expectancy at birth, Infant mortality
rate, and Tuberculosis incidence. We analyze the structure of the data in order
to find the optimal and independent on any expert's opinion way to map several
numerical indicators from a multidimensional space onto the one-dimensional
space of the quality of life. In the 4D space we found a principal curve that
goes "through the middle" of the dataset and project the data points on this
curve. The order along this principal curve gives us the rating of countries.