Research [1, behind a paywall], based on data from Olmsted County, Minnesota, shows:

"the incidence of parkinsonism and PD may have increased between 1976 and 2005, particularly in men 70 years and older. These trends may be associated with the dramatic changes in smoking behavior that took place in the second half of the 20th century or with other lifestyle or environmental changes. However, the trends could be spurious and need to be confirmed in other populations."

Reference

[1] "Time Trends in the Incidence of Parkinson Disease"
Rodolfo Savica et al.
JAMA Neurology, June 2016
JAMA Network | JAMA Neurology | Time Trends in the Incidence of Parkinson Disease

John