One should not get too hung up about words, particularly those related to French concepts.
In English language books neither equality or fraternity are used very much. Liberty is far more popular. Perhaps Tom Paine managed to have some influence after all, if only by transmitting one of the three concepts the French Revolution launched upon the world. After his death the word begins to fall out of English writing. It is a calamitous decline, from 0.016% down to a current 0.0025%, a 6 fold decline. Liberty has gone out the window, has been ground down to the ground.
Alarmed, I sought to console myself with democracy but this proved a disappointment. It is only a little more popular than equality and fraternity. It seems to be a World War hangover. It comes up a bit after the first round of slaughter in 1920, and rises a bit higher after the second round in 1943 to a peak of 0.0058% and declines somewhat thereafter. It was a slogan which hasn’t really caught on.
This counts as a finding, at least in the social science sense of that term. I have tracked a slogan and found a story with a moral. We have lost our liberty. Cue the credits, and a lachrymose swelling of violins.
Before jumping to conclusions, it is best to consider trivial alternatives.
Freedom is a word I rarely use
Without thinkin', mm hmm,
Taking the great thoughts of Donovan as my cue, freedom comes to the rescue. More popular than democracy but aping its general form, it surpasses liberty in 1906. These may be matters of emphasis and nuances of meaning, but freedom seems to have gained the edge by virtue of suggesting the unrestrained exercise of rights, whereas liberty is perhaps more political.
Finally, I cast about for a concept to act as a control variable, something which would put these important political and social ideas into context. My first, and rather cynical choice fits the bill perfectly. By 1800 it was a bit more popular than liberty and added to its popularity till the 1930s, from whence it had a period of decline, but is now almost as popular as two centuries ago. Political fads may come and go, but every scribbler knows what really matters, because no-one but a blockhead ever wrote, other than for money.