Corpora: Neologisms in Japanese

[Wolfgang Hadamitzky]

I have been trying out in vain to find statistical data or literature (in
Japanese or other languages) on the following topic:

What is the percentage of words written in katakana or kanji respectively
among Japanese neologisms since 1945 and especially during the last decade
(1991-2000)?

A second question:

What is the largest corpus of Japanese words and proper names that can be
accessed online?

As I am not a member of the CORPORA list any answers to my private e-mail
address are welcome.

Sincerely
Wolfgang Hadamitzky

w at hadamitzky.de