Could less show the viewed proportion of text file?

If you open a file with less then pressing Ctrl-g will display the current line number, total lines and percentage as well as shown below:

lines 51-100/185 byte 3228/5886 54% (press RETURN)

Do you mean like with the -M switch?

less -M +Gg

for not very big files it's OK, because +G (G command) go till the end of file