I imported the pge_summary.csv file, and the data for some countries seem to be greater than one, when the PGE supposedly ranges only from zero to one. How can I interpret these data?

The issue here is that the pge_summary.csv file is saved using RFC 4180 csv conventions, that is, with a dot marking the decimal and a comma separating values. If you are in a locale that observes different conventions—many countries use commas to indicate the decimal and semicolons to separate values—your software’s default settings may not read the data correctly. Be sure to specify the decimal marker and value delimiter appropriately when loading the file: all PGE values fall between zero and one.