Google has graphed the growth of UTF-8 unicode on the web. This year Unicode use passed the extended ASCII used to cover the English language and some European languages. It's growing on a classic exponential curve, all the alternatives are in steep descent.
There are good reasons to use Unicode even with English, but that's not driving this transition. Unicode's growth reflects the use of Hindi, Chinese and other non-european languages on the net.
This graph is another milestone in the post-euro world.