As of the 2010 United States Census of 2010, there were 173,514 people, and 62,400 households. The population density was . There were 74,537 housing units. The racial makeup of the city was 79.4% African American (U.S. Census) or Race (United States Census), 18.4% White (U.S. Census) or Euro American, 0.1% Native American (U.S. Census), 0.4% Asian (U.S. Census), and 0.9% from two or more races. 1.6% of the population were Hispanics in the United States or Latino (U.S. Census) of any race. Non-Hispanic Whites were 18% of the population in 2010, down from 60% in 1970.

Based on the above article, answer a question. How many percent did the non-hispanic white population drop from 1970 to 2010?
42