Last decade I'm not so sure. I bought the very first readily available consumer quad core CPU a decade ago (the Q6600), two years ago I upgraded and I had to pay a huge premium because I wanted more than four (I got six!) cores. And that is just starting to change today.
Not that core count is everything but consumer desktop CPUs have stagnated quite a bit. Here's to hoping AMD stirs it up a bit.
Because the compute power for consumer CPU nowadays is good enough, the effort has been in reducing energy consumption. But if you look at the server / workstation side, you can get 20+ cores in a single dice.
If you consider core count desktop CPUs have had massive increases in performance in the last year and will get another massive increase when 7nm arrives.
Not that core count is everything but consumer desktop CPUs have stagnated quite a bit. Here's to hoping AMD stirs it up a bit.