To list tags with the tag usage count at the the beginning, run:

buku --np -t | awk 'gsub( /\(|\)$/, "" ) { $1 = $NF; $NF = ""; print }'

or, to sort by usage count:

buku --np -t | awk 'gsub( /\(|\)$/, "" ) { $1 = $NF; $NF = ""; print }' | sort -nr