Well, there are many orders of magnitude more embedded processors than general purpose computers.
About 250 million PC produced per year.
Many billions of embedded processors produced per year.
Global embedded software market is worth about 3.4 billion dollars per year.
Embedded systems (with hardware added) worth 88 billion dollars per year in 2009.
(Now, PC's are worth more than 350 each, so there's more money in PC hardware.)
Lots of embedded processors are doing "the same thing", but embedded is hard, costly and cost constrained, so there is a lot of pressure in the "consumer embedded" space to reuse code.
The mainstream software industry is worth about 300 billion per annum.
The bottom line About 100 times less money in embedded than "normal" software.
But programmers for embedded are often Electronic engineers, getting paid less; or in Asia, where they are paid 5x less than in, the USA for example.
Electronic engineers in Australia often get paid 20% less then software engineers.
So probably about 1/30th as much programming work is embedded.