Excel file shows the frequency distribution used to estimate percentiles for paper In Journal Of Neurodevelopmental Disorders.
NB Because of limited Plunkett norms in this age range, this is based on a sample of only 55 cases, and age range 18.5 to 21 months, which gives mean age comparable to our sample.
The raw data used for norms can be downloaded from http://babylab.psy.ox.ac.uk/research/oxford-cdi