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:
Seattle

Context:
Of the city's population over the age of 25, 53.8% (vs. a national average of 27.4%) hold a bachelor's degree or higher, and 91.9% (vs. 84.5% nationally) have a high school diploma or equivalent. A 2008 United States Census Bureau survey showed that Seattle had the highest percentage of college and university graduates of any major U.S. city. The city was listed as the most literate of the country's 69 largest cities in 2005 and 2006, the second most literate in 2007 and the most literate in 2008 in studies conducted by Central Connecticut State University.

Question:
What is the national average of high school diploma holding citizens?

84.5%