SVRs exceeded yields for all the years of your chart from 1988. I didn't say it was always double. It was triple in 1989 and 1990 and more than double in 1988, 1991, 2008. It was double in 2000, 2006 and 2007. It was nearly double in 1992/3, 1995/6, 2001, 2004/5.
There's nothing unusual about...