Increasing? People have been saying it for years.
Well, the introduction of Chip and PIN in the UK has vastly increased the number of people using the expression. OTOH I’ve almost never seen “PIN number” written down. Perhaps the action of writing makes the writer stop and think what PIN stands for.
Are there many examples of acronyms that have become words, ie losing their capitalisation (as opposed to words which are thought, wrongly, to once have been acronyms)?
Edit: Sorry, forgot to ask what RBI stands for.