tractions p = 0.002542** p = 0.007717**
2012 Retractions p = 0.02562* p > 0.05
2013 Retractions p = 0.001939** p = 0.008092**
2014 Retractions p = 0.01818* p = 0.02703*
2015 Retractions p = 0.04538* p > 0.05
2016 Retractions p > 0.05 p > 0.05
2017 Retractions p > 0.05
Significance codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05