english: They have been around for several years, but they have become more popular in the over the last few years.
non_english: うぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅうぐぅぐぅうぐぅうぐぅうぐぅ