Not very easily unfortunately.
You can look at the individual stats on your hubs and see how many stars you have for view duration - the more stars the better up to a maximum of 5. That's probably your best guide.
You can also look in Google analytics, but you have to remember that analytics can only record an accurate view duration when a visitor clicks through to another one of your pages. For most hubs, only about 10% of viewers will view another page on that subdomain, so it really skews the results.