In summary, data were collected over 5 seasons
from May 2000 to May 2005 on a standardized proforma
by the attending medical officer at academy level
for all age groups, collated locally, anonymized with each
participant having a unique identifier code, and then passed
weekly to the central database at FA headquarters in Lilleshall,
United Kingdom. The number of participants at risk
is given for each year by age group in Table