The size of the seller-financed note market

[Charley Gates]

I just finished Jimmy Napier's book, "Invest in Debt."  In Chapter 2, he states that, in 1982, the size of the seller-financed note market was $75B. 

I believe that the current size of the seller-financed note market is $25-$30B.  

That's quite a large decrease especially considering that $1 in 1982 would have the purchasing power of about $3 in today's market.

One explanation could be that Interest rates were artificially low for a long time (until recently) which may have diminished the need for seller financing. 

Any other thoughts on the difference in the size of the seller financed note market?