In Germany, the official statistics for 2019 state that someone who was fully employed worked 41.0 hours per week on average, when part-time employed the number was 19.5 hours. The average over all employees was 34.8 hours.

Source: https://www.destatis.de/DE/Themen/Arbeit/Arbeitsmarkt/Qualit... (in German). The article also contains a table of the average for a lot of European countries, which range from 30.4 in the Netherlands to 45.4 in Turkey. The article also states that the majority of the differences in the average working hours between the countries are typically due to a different ratio of part-time to full-time jobs.