I was entering random names in Google Ngram when I noticed that in the late 80s to early 90s, there is a bump in the occurrence of lower-case European country names. See for example:
united kingdom: http://bit.ly/16srJju
Something similar happens for most West-European country names. A search for "usa" gives a slight bump too, but for china or russia it's absent.
Upper-case names of countries show no bump.
Does anyone have an explanation? Also: how reliable is Google Ngram?