The PC Pitstop Research Memory Trends chart shows that the percentage of PCs that have more than 4 GB RAM is accelerating.
The chart below shows the average amount of Memory found on PCs for each year since 2008. The overall average found on PCs in 2016 is just under 6 GB.
The chart shows that the increase by year has been fairly linear and that Desktops are growing at a bit faster of a pace. RAM or Random Access Memory consists of integrated circuits of transistor memory cells that are used by the computer to transfer data extremely fast by your processer. Your PC uses this memory to store and access much of the data used in its low level processing. RAM can also be used by your PC to automatically and temporarily store data from your hard drive that it determines is needed to support your current activities.
Adding additional RAM to your system is generally considered a easy and cost effective way to increase the speed of your PC.