Hispanic v. Latino by Google's Ngram Viewer

According to Google's nifty Ngram Viewer, use of the term 'Hispanic' in American English books peaked in the early 1990s and has been slipping ever since. In contrast, 'Latino' has been surging since the 90s. 

(Ngram Viewer by Google lets you graph and compare words and phrases over time, showing how their usage has waxed and waned over the years. The data is derived from 15 million books scanned by the folks at Google and includes all of the major languages.)