.22LR
.223 Rem
.270 Win
.30-06
All these are readily available with wide selection of ammunition. They cover most sporting applications - game size / range the majority hunt.
These would be my guesses where cost / availability is an issue.
Looking at rifle manufacturer brochures for mass producer companies like BSA, Parker Hale, Sako, Tikka, Sauer, Heym, Mark X / Zastava in Europe over the last 50 years or so, the common cartridges chambered for are:
.222 Rem in the past but losing ground to .223, .22/250, .243 Win, .308 Win
.270 Win, 7x64, .30/06, .300Win
