Ethnic Norwegians make up 84.5% of Bergens residents. In addition, 8.1% were Immigrant generations or second generation immigrants of Western background and 7.4% were first or second generation immigrants of non-Western background. The population grew by 4,549 people in 2009, a growth rate of 1,8%. Ninety-six percent of the population lives in urban areas. As of 2002, the average gross income for men above the age of 17 is 426,000 Norwegian krone (NOK), the average gross income for women above the age of 17 is NOK 238,000, with the total average gross income being NOK 330,000. In 2007, there were 104.6 men for every 100 women in the age group of 20-39. 22.8% of the population were under 17 years of age, while 4.5% were 80 and above.

Based on the above article, answer a question. How many more of the population were under 17 years of age compared to those 80 and above, by percent?
18.3