**4. Data**

Data on the structure of RES energy production for the new member states was taken from the Eurostat database for 2010 (Table 1), 2015 (Table 2) and 2019 (Table 3).

**Table 1.** Structure of energy production from renewable energy sources (RES) in the new member states in 2010.



**Table 2.** Structure of energy production from RES in the new member states in 2015.

**Table 3.** Structure of energy production from RES in the new member states in 2019.


Then, the percentage share of eight individual variables describing the volume of energy production from selected renewable sources in total renewable energy was calculated for each year—2010 (Table 4), 2015 (Table 5) and 2019 (Table 6). Initial calculations pointed to strong differences in the levels of percentage share of individual renewable energy sources in total renewable energy from selected renewable sources. The significant differences of the new member states in terms of RES production structure are reflected by the high coefficient of variation of individual variables. Therefore, the presented average values for the percentage share of individual renewable energy sources in the total production of renewable energy, calculated for all countries, have a low cognitive value and only the cluster analysis performed in the further part of the article will allow for a proper comparison of selected countries. In addition, the correlation of the variables describing the countries was not high, which supported the applicability of the Euclidean distance to conduct cluster analysis.

**Table 4.** Percentage share of individual RES in total production in 2010.



**Table4.***Cont.*

**Table 5.** Percentage share of individual RES in total production in 2015.


**Table 6.** Percentage share of individual RES in total production in 2019.

