Return prosepects for the equity markets over the next three years

I'm an undergrad with an interview next week for an investment firm in London. They've told me that I need to give a 30 minute presentation as part of my interview. The question they've given me is:

"What do you think the return prospects are for equity markets over the next three years?"

Any help or advice on where to look to answer this sort of question would be greatly appreciated.

I'm sorry if i've posted this in the wrong place btw.

Thanks

John