Some data shows that rents have already decreased 6 to 10% depending on region and location. My lease terms are currently up for renegotiation. What is a good approach and strategy to ask my landlord to reduce rent?
I love the place but I’m willing to stay for 2 more years if the rent is 10% less. 
Of course, it's "okay," @Derek Vaickus. The question is whether or not your land lord will go for it. This is going to be highly dependent on your individual market and situation. Antidotally, I was on a webinar with a bunch of large operators (1000+ units each) yesterday and they were all saying that their occupancy rates are stable and they haven't seen a decrease in lease ups. If that's the situation in your market, you may not have a lot of leverage. On the other side of the coin, they said they were generally offering 6-months leases with rents flat.
How does your rent compare to the rest of the market? If you're already under market, the land lord may be happy to take his chances with a vacancy in the hopes the next tenant will be at market.
I think your best bet is to do your own research. Compile some data to show real facts on what the market rent is in your area. Market rent and potential "percentage differences" is HIGHLY dependent on area. I'm not even talking the same city. I'm talking the same neighborhood. This is also presupposing that your current rent is at market rent and not already below it, at least to some extent.
In a nutshell, can you find a different rental in the same area that is in a similar condition and has the same "perks" as where you are renting, but has cheaper rent. If not or there aren't many, I suppose it still doesn't hurt to ask, but I doubt you'd be successful. However, if it looks like your rent is too high, then accompany your request with your facts/data that has led you to come to that conclusion. It still may not work. But at least that would be a lot more compelling.
Doesn't heurt to try. Make sure you ask politely. I had a tenant ask once and I offered a $50 a month discount. What about this: Would you move out if you didn't get a 10% discount into a new place for the cheaper rate? Is it worth the hassle? Can you find a place for 10% cheaper that is equally nice or better? Are you a fantastic tenant who laways pays your rent on time and causes zero problems? Are you easily replacable? Your landlord will consider these questions also and make a decision with their opinion of this in mind.
I would bring it up to their attention, who knows they might go for it if your a great tenant. They would rather lock in long term leases versus the cost of turnover which is turning an apartment and the cost and time to screen someone else.