Simplify the following text for a Grade 7 native English-speaking person.
Original: For example , the years 1600 and 2000 are century leap years ; the century years 1700 , 1800 , and 1900 are not century leap years .
Simplified: The years 1600 and 2000 , for example , were century leap years ; the century years of 1700 , 1800 , and 1900 were common years .