What percentage of the pilgrims died during the Winter months

Forty-five of the 102 Mayflower passengers died in the winter of 1620–21, and the Mayflower colonists suffered greatly during their first winter in the New World from lack of shelter, scurvy, and general conditions on board ship. They were buried on Cole's Hill.

44.12%

Explanation:

  this riddles' answer is library.

  the "leaves" are a reference to the books' pages that the library contains; the branches are a network of libraries that connect multiple libraries' collections, resources, and items in a system of a common database, integrating them; the branches' organization are a useful management tool for coordinating the multiple collections many libraries have.