Well actually not.
Market share doesn't actually reflect sales - which have grown.

The US market is mainly Nokia-unaware and the top selling phone before the iPhone was/were the Motorola bla bla ZR.

iPhone has gained market share due to users migrating from a phone to another phone (not a smartphone) since the first iPhone can't even be called a mediocre feature phone. To those users the complexity of menus submenus, widgets, setups camera focus, etc(Symbian) would have been incomprehensible - instead, apple has gained market share by presenting basic features as "innovations" and introducing them to the basic user one step at a time.

Then there's android - and since it's not "cool" to not have an OS on any phone every low end piece of junk now has android - and android has the proper advertising which nokia doesn't.

Nokia - king of the world until 2008. Why only until 2008? Easy, they stopped producing high end devices after N82 and N95 (2007), don't ask me why but they even claimed there's no need for HWA in a phone
Symbian UIQ aka. Sony's touch symbian version went down (exactly because of low-spec devices IMHO but then there was the lack of standards such as USB and micro SD which already brings the iPhone down) and Nokia "smartly" decided it wasn't yet time for touch screen devices as the industry wasn't ready yet.
Nokia was right - since the first two iPhones were a complete mess - but that doesn't mean the users didn't want to go "touch" (I did)
So instead of making a bold move they decided to wait, exactly at the time when everyone else decided they belong to the mobile space as well.

Mistakes or not, things are slowly heading back where they used to be.
IMHO old dinosaurs (Nokia & Apple CEOs) have had quite a hard time adapting - at least Nokia has finally managed to do so.