Passion assets increased by 1.2 percent through 2016 and have risen by nearly 77 percent since the beginning of 2005 according to the latest edition of the Coutts Index. 

Rare musical instruments have taken top place in the index this year, rising by 16.4 percent, while classic cars have seen the largest fall at -10.4 percent. Despite this, cars have gained the most across the index categories since 2005, increasing fourfold over the 12 years represented by the data.

Other collectibles include coins which remains the only category to have registered increasing prices in every year since 2005, rising more than 11 percen...