For reference, that figure is ~75% for the US, and between ~75 and 50% for most EU countries. Fun fact, the largest foreign debt holder of the US is...Japan.
* Huge asset bubble in the 1980's.
* The Nikkei 225 stock market indicator reached a high of about 40k in 1989, but dropped to a quarter with the collapse of that asset bubble, and has not recovered that yet (it just recently hit 30k). This period was known as the "lost decade" [1]
* Japan has had very low (near zero) rates for nearly three decades, more than twice as long as the rest of the world.
* Demographics: the transition to low birth rates, shrinking and ageing population started earlier than most other countries
But see for example the charts (click on "max" to see as far back as possible) on Yahoo Finance for famous indexes of top X companies in each country:
Japan (Nikkei 225): Up 118% today since 1985, but down 29% from 1989's peak https://finance.yahoo.com/quote/%5EN225/
USA (S&P500): Up ~2000% since 1985, technically down ~12% since December but anyone who invested 15+ months ago is still up it's not like a crazy crash https://finance.yahoo.com/quote/%5EGSPC/
UK (FTSE250): Up ~1000% since 1986 https://uk.finance.yahoo.com/quote/%5EFTMC/
Obviously these are limited to the few hundred biggest companies but offer a good snapshot, and it's a similar story if you look at other European countries etc., and a significant problem for Japan (as well as being a metric/indicator caused by significant problems) that their growth has been so far behind.