Correction to: European Journal of Human Genetics advance online publication, 11 May 2016; doi: 10.1038/ejhg.2016.36
Post online publication the authors realised that they had made an error:
The sentence on page 2: 'In the first 5-year period........but this changed significantly in the last 5-year period with 51% positive and 49% negative (χ2=20.6, P<0.0001)' should read: 'In the first 5-year period........but this changed significantly in the last 5-year period with 49% positive and 51% negative (χ2=20.6, P<0.0001)'.