Ours varies, sometimes its 51mbps sometimes 56mbps
Download wise i take the words "unlimited data" very seriously, through youtube alone i'd average about 180gb/month not including amazon, iplayer and general browsing.
I'd say atm you dont really need more than 10mbps for one person, although the overhead for nobody even noticing the other is hogging the internet, and downloading from steam/origin superfast is nice.