If you divide the number of national votes for each party by the number of MPs elected, you find that the Green MP received over 44 votes for each vote received by an SNP MP, and the UKIP MP received over 149 votes for same.
The ratios go like this:
Code:
001.00 SNP
001.32 Conservative
001.55 Labour
011.55 Lib Dem
044.45 Green
149.21 UKIP
I've not bothered to calculate the ratios for the Irish or Welsh Parties - but I expect they would be near the top of the list.
To put it in terms of total votes, UKIP received 2.66 votes for every one SNP vote - but SNP got 56 MPs whereas UKIP got 1.