Several factors.
First, replacement of tubes with capacitors and diodes.
The reduction in size of semi-conductors.
Alan Turing's work in the 1940s led to the development of modern computers. Computers small enough to be used in homes have been available since the early 1980s.
Not enough information to answer... In order to calculate the average number of computers - we would need to know the total number of households !
Yes, smartphones and tablets are small enough computers we can carry with us. Smartphones are usually carried in a pocket! Laptops, though larger, are still also small and light-weight enough to be transported, usually in a briefcase or a backpack.
Computers can range from a mainframe, that could take up several rooms, to computers small enough to slip into your pocket.
Microchip
A personal computer that is small enough to fit on your lap is called a laptop computer or simply a laptop.
workstations A class of computers small enough in size and cost to be used by a small group or an individual in their own work location yet powerful enough for large-scale scientific and engineering applications.
Laptops were names such because they filled your lap. Notebook computers include those the size of your lap and smaller "tablet" PCs small enough to fit in the hand that were the size of a paper notebook.
The first computer was big enough to fill an entire room. Today, computers are so small that people can hold them in their hands.
The development of this chip led to the invention of the first personal computer. With this invention, the use of computers spread from large businesses and the military to small businesses and homes.
in small wooden homes
In general, they don't actually 'make' homes. If they need somewhere safe to rest, they usually find any space small enough for them to fit into - such as a dry log, or under large stones.