Channel Width

This question relates to VOR.
I read that when VORs where increasing continuously in number in the
beginning of their "career" there was a lack of available frequencies.

So they increased the frequencies by increasing the number of chanels
and they did that by decreasing the chanel width e.x from 100kH width
to 50kH width.

Can you explain me please how this(meaning increase of channels by
reducing their width) will increase the number of available frequencies
for the increasing number of VOR stations.