A special usage of AN

Hello everyone,
Please look at this sentence :’‘AN estimated seven percent of British people are now vegetarians and there are a great many others who only eat meat occasionally.’’
I wonder why they use AN here before percent because seven percent is accountable.

‘‘AN estimated seven percent of British people…’’ = A result made by estimation indicates that seven percent of British people…’’

I think it’s because “seven percent” is used in place of the word “number” – an estimated number, the estimated number.

O that would be more outright and clear it up with one shot. :smiley: