Here is an interesting infographic about second language use worldwide from the Business Insider site.
It doesn't distinguish between:
- Official languages used nationally (e.g. Swedish in Finland).
- Regional languages that are not used throughout the country (e.g. Catalan and Kurdish in Spain and Turkey).
- Recent immigrant languages (e.g. Polish in the UK).
It also shows Belerusian (sic) as a second language in Belarus, which is surprising. According to Wikipedia Belarusian is the national language and Russian has official status.