This is a topic that I hold particularly dear. This question is related to data so that it is acceptable for this community. However, as a languages enthusiast, what deeply concerns me is that this explosion in katakana loanwords is (and will be more and more) "re-shaping" a beautiful language like Japanese in a sort of hybrid language (this is of course a very pessimistic view).
Intro: (on purpose a little provocative)
I have just read an answer from Naruto to this question. In particular these last two sentences made me decide to finally start scraping the surface of this topic which I have been concerned with for a long time.
Today, Japanese people no longer frequently coin totally new kanji compounds nor borrow new kanji words from Chinese. Instead, people introduce new katakana loanwords almost every day.
I totally agree, and want to build up on this.
Anyway, I will not ask whether you think or not that "katakana is just ugly, so isn't the less the better"? (Want to have a headache? Look here for example). Would be an opinion.
Although I am extremely curious to know about it, I will not ask "why do you think that Japanese people like so much to just adopt a katakana loanword rather than make up a "traditional" Japanese word for something new? (For example Chinese would (almost) never do that I believe). You would be surprised at the reaction many Japanese people when I ask: so, why has it been called エスかレター and not, say, 自動階段? (I came up with this example myself but people seem to agree that could make perfect sense). Would be probably be an opinion again.
I have the feeling that especially in the last decades the use of katakana loanwords has increased dramatically (and this seemed to agree with the quote above).
When exactly did it start? Do you know of any data/references where one could track the evolution of creation and use of such loanwords? I would be very interested to know what is the growth rate. Also, they seem not only related to technology or "new inventions" but my feeling is that more and more nouns, adjectives, etc are becoming popular (リーズナブル、インストラクター、 ディスカッション， and I could go on forever). So at what pace and why katakana loanwords are growing so much?
Related to this I would also like to clear the following. Again, my feeling and personal experience tells me that Japanese is probably one of the languages with the highest rate of loanwords in the world. Is this true? Is there data to back this theory up?
Bonus question (might be slightly an opinion):
Do you think that using katakana instead of the English alphabet also for words that are normally not considered Japanese words would in the long run (tens of years) contribute to the creation of a new loanword that will be adopted and integrated as a "Japanese word"?
Example: a building is called ビュータワー。 No Japanese today (I hope!) would use ビュー for "view" (they would use 景色，眺め、眺望， or whatever appropriate).
However, wouldn't using English alphabet make a much clearer distinction between what is a Japanese word and what is not? Doesn't using constantly a Japanese alphabet also for English words risk to lead, in the future, to people saying something like "綺麗なビューですね"?
Although it might be difficult to feel this difference from "original" and "loan" words from a native speaker point of view (they probably both would sound natural at the same level), IMHO Japanese is a beautiful language and this extreme growth in loanwords is doing some serious harm. Of course one could argue that every language evolves and will eventually change. But is it wrong to want to protect it's roots structure? I actually met Japanese people that seems to feel the same way I do and would be interesting to continue this discussion.