I'm to 1600 AD and my research rate is at 70%. Is this an OK thing or should i be doing something to get it to 100%?

-Insidion

70% isn't bad. It probably would be worth it to build a few banks or markets to try to get to 80%, but beyond that won't be easy. And 100% is not realistic. With city upkeep and civics costs, you'll have to be pulling in an awful lot of gold from Holy Cities and exporting trade products to have 100% science.

it depends on what your total commerce is. if you have a very large empire and you're researching at 40% you can be outteching a civ with half the cities and not as great of an ecomony that's researching at 80%. it's all about what your total number of commerce is...

Like terriFyer said its not research rate it's beakers per turn that counts (F2).

Banks, Marketplaces and Grocers are all great, but building cottages can also boost your commerce. 70-80% is a great sci output if you don't have a major religious city, just keep pumping along.