Based on a study of 1762 PwP in Korea, Lee et al. [1] used the concept of L-dopa equivalent daily dose (LEDD, see [2]) to offer some insights into regional differences in the doses of drugs that people are taking.

Average LEDD
Korea 608.9 mg
Germany 599.2 mg

Average LEDD immediately before DBS:
Japan 419.5 mg
Taiwan 788.8 - 899.9 mg
Europe 808.5 mg
North America 1074 - 1409 mg
These differences were despite the fact that disease duration and UPDRS scores were similar.

LEDD on average increased during the first 10 years of the disease, but then plateaued.

Reference
[1] "Daily dose of dopaminergic medications in Parkinson disease: Clinical correlates and a posteriori equation"
1Jee-Young Lee MD, 2Jae Woo Kim MD PhD, 3Won Yong Lee MD PhD, 4Jong-Min Kim
MD PhD, 5Tae-Beom Ahn MD PhD, 6Han-Joon Kim MD, 3Jinwhan Cho MD PhD, 6Beom S
Jeon MD PhD
Neurology Asia 2010; 15(2) : 137 – 143
http://www.neurology-asia.org/articles/20102_137.pdf

[2] http://neurotalk.psychcentral.com/thread169655.html

John