The 1st 100 go pretty easy at only 750 per level, it`s after 100 things really start to slow down as it takes 2500 turns to jump a level. At 100 turns per day that`s almost a month per level. I don`t think you`ll ever see a max on normal any time soon... 8]
Highest lvl is 255 but that isnt what he is asking. Because the turn speed is lower on normal people have lower research lvls and he wants to know what the highest someone has is