请教，句式结构

Granted, Switzerland and the United States diverged in the degree to which the expansion of industry coincided with the degree of urbanization: only 29 percent of the Swiss population lived in cities of 10,000 or more inhabintants by 1920.

红色部分是什么结构？句首的Granted 有充当什么成分？请高人指教

to which定从修饰the degree; 而从句中, 是A coincide with B结构.  其中, A是the expansion of industry, B是the degree of urbanization

Granted - Longman解释: [sentence adv.], used when you admit that something is true, 于句首