Families in the UK are decking their halls with advent calendars this year. Specifically, new data from market research firm The NPD Group shows sales of toy-filled advent calendars are up 5% over 2018. The segment posted US$20.8 million in sales (£16 million) up to November 23, NPD found.

One company taking advantage of the mystery-door trend is The LEGO Group, which bowed four of the top-10 best-selling advent calendars in the UK this year. Topping the charts in first and second place were LEGO’s Harry Potter-themed set (pictured) and the CITY Advent Calendar, with its Star Wars and Friends calendars rounding out the list. Playmobil’s calendar and two entries from Funko—the Pocket Pop! Harry Potter  and the Pocket Pop! Marvel 80th anniversary calendars—were also top sellers.

Rounding out the top-10 were surprise box sets for Peppa Pig, MGA Entertainment’s L.O.L. Surprise! and Panini’s Adrenalyn XI Premier League.

According to NPD’s global industry analyst for toys, Frederique Tutt, the toy-filled mystery box category is growing in the UK due to older children, teenagers, young adults and toy collectors purchasing calendars dedicated to beloved brands like Harry Potter, Star Wars, Marvel and Fortnite. Prices for the top-10 best-selling advent calendars range from US$19.64 to US$38.23.