FiREapps Q1 2018 Currency Impact Report shows that the currency impact was far greater for European MNCs than for North American MNCs:

Source & Copyright©2018 - FIREapps

And that the top volatile currencies weighted by GDP are still CNY and EUR: 

Source & Copyright©2018 - FireAPPS

While the uncertainty of Brexit has impacted GBP as it rose one place since Q4 2017. 

(See FIREapps reports here.)