The monthly pattern of visits in 2021 will have also been influenced by any COVID-19 restrictions in place limiting travel at different times of the year.
Byddai unrhyw gyfyngiadau teithio a oedd ar waith oherwydd COVID-19 ar wahanol adegau o’r flwyddyn hefyd wedi dylanwadu ar y patrwm ymweliadau misol yn 2021.