You've got to be kidding. A "trend"? Is it a trend to call people from Europe "Europeans"? Or from Asia "Asians"? Or just the fact that people from certain regions are called by that region proper adjective? For America (name of the supercontinent comprising South America and North America), said proper adjective is "American", like it or not, and not a "trend". I'm Uruguayan, therefore American. Once again, you like it or not. The name America for the region was in use for a good quarter of a milennium prior to the foundation of USA. From where do you think they got the name? (By the way, "United States" doesn't cut it either... There are more United States in America.)
You've got to be kidding. A "trend" I have to recognize that this may be a lost battle, however. On certain Asian country I was asked by person in the street if I were American. I answered "Yes, of course"... and then was insulted. Since it was in the local language I have no idea what he said (only recognized the word "America" a couple of times). My host, the one that told me I had been insulted, refused to translate and just told me not to pay attention to ignorant people... what I did.