chances of flush vs flush

[jacknine]

Im playing a 5-handed hold´em game. I am dealt 6[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/spade.gif[/img] .
Flop: 8[img]/images/graemlins/spade.gif[/img]K[img]/images/graemlins/spade.gif[/img]T[img]/images/graemlins/spade.gif[/img]

Now, what are the chances of me losing this to a higher flush?
I´ve taken the chance of someone having a higher flush on the flop + someone having 1 higher spade than me and another spade coming off on the turn/river. I came up with approx. 8% chance of losing to a higher flush. Correct?

(Im not taking into account anybody having a str8flush)