**Author details**

Jiřina Kocourková Department of Demography and Geodemography, Faculty of Science, Charles University, Prague, Czech Republic

\*Address all correspondence to: jirina.kocourkova@natur.cuni.cz

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
