I would be interested to know if they are saying the people who actually send spam are sending less or people/businesses have just gotten better at blocking it.
I certainly still get plenty but I use a Yahoo account as my trash e-mail magnet (it gets flooded with spam) and keep my personal e-mail private with just friends and family so it is usually clear. I also almost religiously tell anyone who sends me unsolicited e-mail to stop it (usually companies and those are usually good these days about providing a simple link/reply system to get it to stop) further keeping my main e-mail almost totally clean of spam.
I have an unscientific measure of spam that would tend to support that, at least recently. I have a Yahoo account that puts most of my spam in a spam folder, then deletes it after 30 days. I never empty it so I can watch the accumulated spam rise and fall over the past 30 days. For a long time it hovered around 3700 pieces, then it spiked up to 4400. In the past week or so it has declined to 3900, so it has gone done some recently, but is up over the long run. YMMV.