How rare is Maine's "blue wave"?

Troy Jackson's win in Maine last night ended Susan Collins' nearly 30-year tenure and gave Democrats their first Senate victory since 1982.

Here's how Maine voted in midterms over the past 100 years.

'President' indicates the candidate that the state voted for in the previous Presidential election cycle. Senate results reflect the most recent election as of each midterm year, including elections held during presidential years. Because Maine has two Senate seats, some victories may not appear.
Chart: Tejal Wakchoure/NBCSource: U.S. Senate, National Governors Association, Ballotpedia