You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Human_Development_Index

Context:
The report showed a small increase in world HDI in comparison with last year's report. This rise was fueled by a general improvement in the developing world, especially of the least developed countries group. This marked improvement at the bottom was offset with a decrease in HDI of high income countries.

Question:
Which countries experienced a decrease in HDI?

high income countries