This tool allows you to view how often case-sensitive comma-separated phrases appear in Google Books (until 2008 as far as I can see) from various languages. Interesting to see

Love

scores a lot lower than

Sex

and “yes we can” was popular in 1930 – 1935 as well as 1944 – 1950 and started on a growth well before Obama came along in 1990.

Oddly enough, “I have a dream” has also been making a comeback since the 1980s