Simplify the following text for a Grade 4 native English-speaking person.
Original: The discovery of rich manganese deposits in Serra do Navio in 1945 revolutionized the local economy , but AmapÃ did not achieve statehood until October 5 , 1988 , with the promulgation of the new Brazilian Constitution . The State of AmapÃ has also the lowest rate of loss of its original vegetation of any Brazilian state : only 2 % .
Simplified: AmapÃ has only been a Brazilian state since 1988 .